Review & Install Video
Hey, everybody. I'm Justin with americanmuscle.com, and welcome to my detailed breakdown and install of Eibach's Pro-Plus Suspension Kit, available for your 2015 and newer Mustang GT. We'll cover some of the bigger points of the installation, and there is a fair amount of work involved here. But it's all very straightforward nut-and-bolt stuff, so I'm gonna go middle of the road two out of three wrenches on the difficulty meter with some more detail later on.So the Pro-Plus Kit from Eibach should appeal to the 2015 and newer owners out there looking to take care of both the handling and appearance at the same time, using a couple of quality components from a name like Eibach. Now, first up, these Pro Kit springs will drop your car one inch on all four corners, making them a great choice for the owners who wanna get rid of some of that wheel gap. But not slam the car to the ground at the same time like Eibach's other turnkey package, their Sport-Plus Kit. Finally, the sway bars will be an upgrade in diameter over the factory bars you're gonna be replacing. They are gonna offer some adjustability as well, really tightening up the car in the process and helping you reduce some body roll.But let's break this kit down a little bit further here, and let's start with these Pro Kit springs. Now, as a Mustang fan, Eibach has always been one of the most trusted names in suspension, and that certainly still applies here today. Now, as far as Mustang springs are concerned, Eibach keeps things pretty simple. You wanna go low, you go with the Sportlines. If not, you do the Pro Kit springs, which we have here, and that does still apply to the S550 spring offerings.As far as that exact drop, well, you're looking at just over an inch up front, one inch exactly for the rear, and this tends to be the sweet spot for the S550. And as a result, it's a drop you're gonna see with a lot of the aftermarket springs in the category and for good reason, right? Because it's enough to get rid of that wheel gap but not enough or low enough to be dragging over every single speed bump or driveway in town. But again, if you really did wanna go lower, check out those Sportlines like we already talked about. You're looking at 1-1/2 inches all around, giving you a more modified or aggressive stance, and you can pick up the Sportlines by themselves or in the Sport-Plus package, as it's called here on the site, for the exact same price as the Pro-Plus Kit here.Now, the Pro Kit springs do also feature a progressive spring rate. And what does that mean? Well, it's something that you're gonna see with a lot of aftermarket springs because it's going to offer the best of both worlds. You're gonna get a softer initial spring rate here with the Pro Kit springs or other progressive springs, making them good for daily drivers out there. Gonna be a little bit more comfortable while cruising, and then, once the spring starts to compress a little bit more, those spring rates tend to firm up, offering you improved handling. So again, I like to think of this as the best of both worlds.Now, these spring rates exactly, well, you're gonna looking at 200 to 314 for the front, 800 to 914 pounds for the rear, so you are getting a little bit of a range there between that softer initial spring rate and the firmer final rate. Now, that lower center of gravity working with that firmer spring rate will help improve a couple of different areas in your car's performance. You're gonna see less body roll, so the car's gonna feel a little bit more confident in turns, a little flatter, as we like to call it. You're gonna see less nosedive when you really stab the brakes and a little less squat when you're really gettin' on it. But again, the springs are only one-half of the equation here, gang. As you can see, we also have Eibach's Front and Rear Sway Bars. They are three-way adjustable, and in my opinion, they are gonna offer a huge upgrade over those factory sway bars. As far as exact diameter, well, you're looking at 35 millimeters for the front, 25 millimeters for the rear. Both bars are tubular, and that is nice because it's gonna help save a little bit of weight, compared to the heavier, solid design, without really compromising any rigidity.Now, I've said it once, and I'll say it again. I tend to think these cars are just a little under-barred from the factory to better suit the masses, as opposed to you and I, the spirited drivers. So by upgrading the diameter for both front and rear bars, giving you that adjustment, it's gonna work with the springs in helping to reduce your body roll, of course. But it's also gonna help the car just rotate through the turns a little bit better. And what do I mean by that? Well, anybody's that driven these things hard probably have noticed the fact that the cars tend to plow or push through the turn, as opposed to rotate. This is called "understeer," and it's something that you can help dial out with the addition of an aftermarket adjustable bar from Eibach.So again, with the bigger bars in place, you can set up a neutral balance to the car or maybe even set up a little bit of oversteer, depending on how you adjust the bars themselves. Totally up to you. Everybody has a different driving style. I would just suggest playing with your settings and seeing what works best for you. Regardless, I can guarantee you that once the springs and sway bars are installed onto your S550, the difference or improvement in handling performance is just gonna be so noticeable it will really blow you away. And in fact, don't take my word for it, guys. Feel free to check out our Customer Review section. We get a lot of feedback on the site from guys who have actually installed this kit on their S550, have pounded the pavement with it, and I'm sure you're gonna like some of their responses.But getting back to these bars here, again, they are three-way adjustable for both the front and rear bar, and it's essentially gonna allow ya to soften or stiffen the bar up, depending on your driving style. As a rule of thumb, Eibach always like to recommend starting with the middle hole and just kinda working from there to dial in your optimal settings. The bars themselves have been constructed from cold-formed, high-strength aircraft grade steel, finished in the red powder coat that you see here just to help reduce any corrosion over the years. Now, the sway bars themselves do not actually include any end links here, but I'd strongly suggest picking up a set of adjustables for the front, especially if your S550 is lower. They're also throwing in some nice stuff here with the rest of the kit, greaseable polyurethane bushings for both the front and rear sway bars, you're getting some dust boots or dust covers for the front struts, and they're also giving you some bump stops with the kit as well.As far as price is concerned, well, you're gonna be looking at just south of 700 bones here for the Eibach Pro-Plus Suspension Kit. Which, in my opinion, guys, really isn't all that bad when you consider what you're getting here, an extremely high-quality suspension kit that's been designed to work together in harmony. And basically, Eibach has just taken all of the guesswork out of this thing for ya. And believe me when I tell ya, guys, this is just one of those parts that you're really gonna feel the moment it's been installed and the first time you go around the block.But let's touch on that install here briefly, guys. And as I pointed out earlier, yes, there is a fair amount of work and elbow grease involved with this installation, but it's all very straightforward stuff. And in fact, most of it can be accomplished with a basic socket set, a few open-ended wrenches, and some other random hand tools. So I'm sticking with two out of three wrenches on my overall scale of difficulty here, maybe a few hours to a half a day in the shop or garage to get knocked out, depending on your level of expertise. And of course, don't forget your spring compressor for this one, as it will be needed. Now, in addition to those tools I just talked about, you're also gonna need to get the car in the air slightly using a lift or jack and jack stands, if you like.Now, the fronts, in my opinion, are definitely gonna be the more time-consuming part of the install. The entire front strut assembly needs to come out, swap those springs using your spring compressor, and then reassemble in reverse order. The rear springs on the IRS-equipped S550 will be a little bit more tricky, compared to the solid rear axle cars of previous generations, but still not that bad overall. Instead, you're just gonna need to loosen those rear sub-frame bolts enough to let the sub-frame sag, remove those factory springs, swap in the new Eibachs, and you should be good to go there.As for the sway bars, well, the rear bar you can do in your sleep. That is very straightforward and very easy with the car in the air. The front might take a little bit more work because there are a couple of brackets you need to hit through the engine bay. So grab all of the extensions in the toolbox and knock those out. And I think having a buddy on hand to help you kinda fish the front bar through the engine bay just makes life a little bit easier. But maybe your experience will be a little bit different. Regardless, guys, I always like to encourage you. Go to an alignment shop after the install. Please, just do it. You're only gonna be doing yourself and your car a favor by making sure everything is in spec.And with that in mind, this is a great time to bring up some possible add-ons here with the Eibach Pro-Plus Kit. Now, because this is a very mild drop, you're probably not gonna need any aftermarket caster camber plates or anything like that because the factory stuff should offer enough adjustment to get you back into spec. That being said, it's never a bad idea to give you a little bit more play with your alignment settings if you are really into road racing and that sort of thing. Also, guys, if you're putting this stuff on relatively low-mileage dampers...I'm talking shocks and struts here...you shouldn't have too much of an issue. However, I'm always gonna tell ya aftermarket shocks and struts are designed to work better with a lower ride height and firmer spring rate of an aftermarket spring. So if that's something that you can factor into the budget, your car will definitely react a little bit better accordingly.But what do ya say we stick a fork in this one, guys. The Eibach Pro-Plus Kit is gonna offer a lot of bang for your buck for your S550 GT. And what do I mean by that? Well, the improvement in handling will be night and day, compared to the factory components you're replacing, and the improvement in appearance, thanks to that lower ride height, certainly doesn't hurt either, right? So, guys, that is gonna do it for the Eibach Pro-Plus Kit, which you can grab for your S550 GT right here at americanmuscle.com.