Free Shipping On Orders Over $75. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Up to 60% Off Sale Shop Black Friday >

MP Concepts Quad Exhaust Rear Diffuser (15-17 GT Premium, EcoBoost Premium)

Item 398118
Call a Mustang Enthusiast at 1-877-887-1105
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Market Price $345.99 You Save 27% ($94.00)
Our Price

$251.99 (each)

FREE Shipping

Open Box from $37.80

Will this fit your Vehicle?

Select a different vehicle Help?
Update or Change Vehicle

Item Options

In Stock

Ship to: Ashburn - 20149
Sorry, please enter a valid US or CA postal code
We're sorry, zip can't be updated at this time.
    Create a list
    Add to New List

    Saved - View your saved items

    We're sorry. We couldn't save this product at this time.

    or use

      Video Review & Installation

      Hey, guys. Adam here with And today, we're taking a closer look at and installing the MP Concepts Quad Rear Diffuser, available for the '15 to '17 GT Premium and EcoBoost Premium. First and foremost, guys, you should be checking this out not only if you're looking for a more aggressive rear end, but also if you're looking to convert from the factory single-tip exit to a quad-tip exit. Now, as you can see, we have this installed on our '15 GT Premium, which, of course, came with a single exhaust tip from the factory but it does now work with a quad-tip exhaust. And if you're not looking to spend the big bucks on a full quad-tip catback or axle-back, you can pick up MP Concepts' sold separately exhaust tips that bolt right up to give you the quad-tip appearance. So, with that, there's a ton of different ways you can customize this to make it your own. You can pick up any number of exhausts out there that have a quad-tip exit, but now you can also pick up some of the preset ones that bolt right up to the inside of the diffuser that go right over your factory single-tip to make it now look like a quad-tip. Now, of course, the diffuser itself has a lot more to offer than just converting from single to quad tips. You can see that the fin section in the middle where your reverse light is is completely different. Your premium option had a pre-painted section there with two fins that is now converted to a fully matte black injection-molded plastic with a very fine grain textured finish, and it now has four fins to give you that more aerodynamic race-inspired look. Overall, just a more aggressive rear end, not necessarily paint match anymore, but it is paintable if you'd like to get it paint-matched at your local custom shop.Now, while this does not come with quad tips, the rear diffuser itself comes in right around about 250 bucks. And if you're looking to pick up the MP Concepts bolt-on tip separately, they're are another $150 to $165, depending on which option you go with. Now, of course, you don't have to pick up the MP Concepts quad tips to make it work, it can work perfectly with your single tips although with that bigger cutout there, you definitely want to fill up some of that negative space. In which case, I'd recommend taking a look at some of the quad-tip exhausts in the category for that conversion. Now, for the install, I'm giving a two out of three wrenches on our difficulty meter not because it's anything too difficult, but there are some extra steps you have to take to get it done properly. You do not have to remove the entire factory rear bumper, you're just going to be unbolting the factory valence there, and then transferring over some of those components to your new option from MP Concepts. With that said, though, there is one small section that you have to cut. On each side of your factory reverse light, there is a molded section that connects the pre-painted part to the bumper itself and you got to cut those off. It's a couple of very simple, straight-line cuts, and we already had ours cut but I'll show you exactly where you have to do that. If you ever want to revert back to stock, even though you did cut it off, it'll still bolt right back up and be held on perfectly fine. With that said, guys, the entire install will take you about two hours from start to finish. I'm going to show you guys what that looks like. What do you say we get started?Tools used in this install include an impact gun, a ratchet, couple of extensions, 7 and 10-millimeter deep sockets, Phillips head socket or a Phillips head screwdriver, panel removal tool, and a small flat-head. All right. Getting right to it, you got to put your vehicle up in the air, whether that be on jack stands on the ground or using a lift like we are here. The lift makes life a lot easier, but we have access to that, if not, the floor will work just as well. The first thing you're going to do is start at the rear here where the bumper connects to the inner wheel. Well liner, there are three 7-millimeter bolts you can access from the wheel well. We're going to do that on both sides and then everything else is just underneath. So, I'm starting with a 1/4-inch ratchet, a small extension, and a 7-millimeter deep socket. There are two 7-millimeter bolts right here facing out that way, and then there's one facing directly up and down, which we're going to tackle third. So, grab your ratchet, get those two off here. They're going to be very difficult to see, but if you just peek your head in there, they're pretty easily visible from the inside. So, just get those two out of the way, then we'll move on.All right. So, we're just peeking your head in there, there's one right here. So, I'm just gonna work that guy off. All right. So, there's one. Directly below it, there's another. All right. So, with that out of the way, we can peel this guy back. I'm just going to prop it up behind that tire and then sticking straight up and down is another guy down here. So, we're going to get that off as well. All right. So, here's the one facing directly up. There are two more right here and here, but we can access them from underneath, this is the last one in the wheel well. All right. So, we got this guy out. Now, we can repeat that on the other side and then head underneath do the rest. All right. So, next, we have the vehicle up in the air a little bit higher. We're doing the exact same thing we did over here, we can see we have one more 7-millimeter here facing up but there's also one in the middle and you can't see it past this plastic trim piece, but you can go right on top of it and get it off. So, we're going to do that for both of these on both sides.All right. So, there's that. Do the same thing for this one. All right. Do the same thing on the other side. All right. Now, you can see on this bracket here, there is a plastic push pin clip. There should be two, ours is missing one. That's pretty common nowadays, especially if you have a used vehicle. So, you want to make sure you're getting both of these off if you have two. I'm going to get this remaining one off here. Going to use a panel removal tool for this. All right. So, now we're looking at our factory reverse light. Let's unplug it as the first step. Just have that wire dangle there. There are four Phillips head screws holding this on, two here at the bottom, two at the top. The top is a little bit more difficult to see, but it's still easily accessible. You can use a Phillips head screwdriver. I also have a Phillips head bit on my impact gun, so that's what I'm using here. All right. So, now, we can pull this out and set it aside. Now, on the valance, we have two of these pushpin clips, one on each side. Grab your panel tool and get these guys off. All right. So, now, we can pull off the actual valance trim. So, you're gonna start from the outside and just work your way around, pulling straight back to disconnect.All right. At this point, this pre-painted color-matched valance piece has to be cut off. Ours is already cut off from the past, we've done this before. So, just know that ours has been cut, but you will have to cut this guy off. It's molded to the bumper all in one piece, and you can see straight across where we made that cut. So, originally, it sat here just like that, you can grab a body saw or really any cutting tool that you have and you feel comfortable with just to cut a straight line right through the middle there and it detaches and comes off. If you ever want to go back to stock, just like we had it here, it can literally just sit in place right up against it, and when that plastic trim is back on the factory valance, it holds it back in place. So, even though it's cut off, it can still go back to stock no problem. Ours is already cut so we're just going to move forward.All right. So, we got our factory valance off of our '15 GT Premium and it's on our rack here underneath of our new MP Concepts Quad Rear Diffuser. Let's go through some similarities and differences here. And the first thing I want to start off with is something that jumps out immediately, and it's the paint match versus the matte black. Now, that middle section that you had to cut off of the factory rear bumper, and just to reiterate ours was already cut, but you definitely have to make that happen in order to make the swap here. Once you have that cut off, you can clearly see that that paint-matched portion there that has two fins, one on each side, is now being included and molded into the entire rear valance piece and now has four fins. Now, that quad fin is going to help match up to the quad-tip styling if that's the route you're going with this rear diffuser, and it's also just going to give it an overall more aggressive race-inspired design that gives you more of that aerodynamic look to the rear end there.Now, the entire material here is constructed using the same exact injection-molded material there using all OEM CAD data from Ford. So, it's a perfect fit to the factory rear bumper on the Premium S550. Now, the nice thing about this is it's got a fine stipple texture. What that basically means is it's a textured matte black finish that is so fine-grained that if there's any rocks that hit it or chip away at it, those rock chips will be hidden in that textured finish. So, it's something that is extremely forgiving over time. It can take the beating. It looks really aggressive and can hide some of those blemishes it may develop inevitably over time. Aside from the obvious color match change to the matte black with the quad fins, the other obvious change is going from the single-tip exit to the quad-tip exit. Obviously, your factory valance only has small cutouts to only work with the factory type single-tip exit. Your new quad-tip rear diffuser, however, it's going to convert it to something similar to the '18 plus GTs that come with factory quad tips. Now, this is a much larger cutout there. A little bit more rectangular in the design there to accept quad tips. I will say that there are accessories you can pick up separately if you're looking to pick up this rear diffuser, but keep your factory single tips on your '15 to '17. There are inserts you can make sure that you're filling in that negative space so it just accepts the single-tip. So, there's a lot of variability with this to make it custom to what you are looking for. You can pick up some of the aftermarket tips for the MP Concepts, or you can just keep it single and use some of those inserts.Now, at the end of the day, the nice thing about this is it is going to bolt or snap right into place on that factory rear bumper and you get to transfer over the factory reverse light right into the middle there. We're actually going to do that off-car just to make life a whole lot easier. And then you're going to transfer over, of course, the reflectors there from your rear bumper and snap them into here. Ultimately, the install process going in reverse is going to be a lot simpler than the uninstall process because there's no cutting or trimming or anything like that after getting the factory stuff out of the way. With all that said and done, guys, obviously, super-aggressive compared to your factory one. What do you say we get this installed on our '15 Premium?All right. So, let's transfer over those factory marker lights, and we're looking at the back of the factory rear valance that we took off. On each side, there's that marker light on the outside here, but it's held on by one nut and a metal clip. Grab a 10-millimeter socket, and we're just gonna get that nut off. All right. From there, you can push this guy out and transfer it over to the new valance, which we have right above it. All right. So, once you have that push all the way in, you should hear a little click. Thread on that nut and tighten it down. And then we're going to do the same thing on the other side. All right. Same thing on the other side. So, I just lifted this guy up so you see it a little bit better. Put the clip in first, snap it all the way in, make sure you're seating it all the way in, you'll hear that click. And then put the nut back on.So, now we have to snap on our extension pieces for the edges. They are side-specific. Keep in mind though, as this little bracket here will attach to the black trim underneath of the vehicle, this is going to bend upward when we go to install it on the car. But for now, we don't have to worry about that. We're basically just going to clip this onto the edge. So, when you look at this, there's two tabs on the inside and it can be pretty tricky. The bottom one is going to slide up through this open slit and move forward to slot into place. This guy has to go in and slot into place. So, you want to make sure you're lining them both up properly. If you need to grab a flat-head screwdriver to help you line up that top one, you can do so just to help push it in. Once you have it seated, it should snap in and sit flush. All right. There you go. That'll snap in. And then once it's installed on the vehicle, these two will bolt in and they'll sit flush like that. Do the same thing on the other side. All right. There you go.All right. So, next, we can focus on installing our reverse light. The reverse light, however, requires spacers which are included in the kit. These little threaded spacers are going to go between the holes where the Phillips head screws will go and the light itself. So, it will sit just like that. So, what we're going to do now is take our factory screws, the Phillips heads, and we're going to line everything up, make sure that the spacer is in place. Put the Phillips head through the light, through the light like that, and thread it into the spacer. All right. So, we should get one in position and start to tighten that guy down. We don't want to fully tighten it just yet just so it holds the whole assembly in. Again, I'm using my impact gun and my Phillips head bit. So, that's just going to hold it in. It's not too tight. You want to make sure you're threading everything else in with the spacers as well. Phillips head first, spacer over the threading, line it up to the holes and thread it in. All right. Do the same thing on the bottom. All right. Once you have all the spacers in position, tighten down all four screws.All right. Last step for transferring things over. On the edges here, we have the pop off these three U-nut clips. So, let's get a small flat-head. We're basically just going to peel those off. You may not need the flat-head, makes life a little easier here. All right. Let's transfer them over. When you do transfer them over, just make sure they're facing the right direction with the threads up. All right. Same thing on the other side.All right. First step here is to pick up the entire valance, line it up in the center, and snap it on. It may prove to be a little tricky at first, but once you start getting them snapped in the middle, it can hold itself on, and you can work your way around the edges. All right. Once you get back to the edge here, it's not a snap, remember it was those 7-millimeter screws. So, they will help line those edges up. All right. So, now, we're going to start putting things back together here, starting with the pushpin clip right here holding on the center section of the valance, do that on both sides. And then we're going to put the screws back in. All right. So, now, we can start putting the three 7 millimeters back on the edges. I'm going to start from the inside here. You want to make sure that everything is lining up. This looks like it screws in pretty easily. And you can start tightening them down with your 7 socket. Remember, this one goes right through the middle. All right. So, now, we can do this one here down here at the edge. All right. Do the same thing on the other side. And then we can finish things up in the wheel well, and then plug in our reverse light.All right. Now, if you remember back to the uninstall portion of the video, this tab is facing up at a 90-degree angle and connected to this bracket here. So, the new valance has the bracket but it has to be bent upwards, and you want to connect these two guys. There's two pushpin clips that go right here. Remember, ours was missing one over that section, but we still have one to put through here and snap that down. Again, you should probably have two there and then repeat on the other side. All right. Now, remember in the wheel well, there's two of those 7 millimeters but we got to pull back down on our liner, and then we're basically going to bolt that shut. Grab both of the remaining 7 millimeters for both sides and tighten them down. I'm just going to put both in by hand and then use my ratchet. All right. Repeat on the other side. Last step here, guys, make sure your reverse light is plugged back in, and you hear that click. And then from here, if you want to install some of those exhaust tips that MP Concepts offers, you can do so, but you're good to go.That's gonna wrap up my review and install for the MP Concepts Quad Rear Diffuser, available for the '15 to '17 GT Premium and EcoBoost Premium. You can pick yours up right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Aggressive Race Inspired Styling
      • Durable Injection Molded ABS Material
      • Features a Stippled Grained Texture
      • Straight Forward Installation - Cutting Required
      • Backup Sensor Compatible
      • Intended for use with Aftermarket Quad Exhaust Systems
      • Designed for Premium Chassis Packages Only (Trim Levels: 200A/201A/400A/401A)
      • Fits 2015-2017 GT Premium and EcoBoost Premium Mustang Models


      Race Inspired Styling. Add an aggressive race car inspired appearance to your 2015-2017 Premium Package Mustang by installing a MP Concepts Quad Exhaust Rear Diffuser. Designed for use with aftermarket quad exhaust systems, this Diffuser nicely compliments the lines of your Premium Package equipped Mustangs rear bumper cover.

      Quality Construction. MP Concepts manufactures their Quad Exhaust Rear Diffuser from injection molded acrylonitrile butadiene styrene (ABS) plastic using the original OEM CAD data from Ford to ensure a perfect fit. ABS is an extremely strong material known for its light-weight, superior durability and impact resistance - making it perfect to withstand the hazards of daily driven vehicles. This Rear Diffuser is completed in a fine grained stippled texture for a factory look that helps to hide the appearance of rock and stone impacts.

      Straight Forward Installation. Installation of the MP Concepts Rear Diffuser is simple and straight forward. However, it will require permanent modification to the stock rear bumper cover to remove a section of the factory diffuser. Installation can be completed in about two hours. Reuses factory reflectors.

      Backup Sensor Compatible. This MP Concepts Rear Diffuser can be installed on Mustangs equipped with or without factory installed back-up sensors and will not affect sensor operation.

      Application. This MP Concepts Quad Exhaust Rear Diffuser is specifically designed to fit 2015-2017 GT and EcoBoost Mustangs equipped with the factory Premium Chassis Packages only (Trim Levels: 200A/201A/400A/401A). Intended for use with aftermarket quad exhaust systems.

      Please Read. If you are having trouble determining what style bumper your Mustang is equipped with please refer to the comparison image above.

      MP Concepts



      MP Concepts 398118

      CA Residents: WARNING: Cancer and Reproductive Harm -

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Diffuser - Center Section
      • (1) Diffuser - Left Side
      • (1) Diffuser - Right Side
      • (4) Spacers

      Customer Reviews (19)

        Questions & Answers

        10 More Questions

        Will It Fit My Mustang

        • EcoBoost - 15, 16, 17
        • GT - 15, 16, 17