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SLP Catted X-Pipe (99-04 4.6L)

Market Price $454.95 You Save 4% ($18.00)
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  • Item 23008
  • MPN# M31032

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Features & Details

  • Increases Horsepower and Torque
  • Race Car Growl
  • Three-Piece "Modular" Design
  • High-Flow Catalytic Converters
  • 2.5" Mandrel-Bent Stainless Steel Tubing
  • Fits 99-04 GT, Bullitt, Mach 1, and Cobra
More Power and Torque. The SLP X-Pipe uses free-flowing mandrel-bent tubing with a genuine X style crossover and high-flow catalytic converters to provide a significant increase in horsepower and torque over the restrictive stock catted pipes.

Race Car Growl. This free flowing SLP x-pipe for the 1999 to 2004 Mustang's not only increases power, but it also adds a raspy, race car growl to the sound of your exhaust with its modern "X" crossover pipe design.

Upgradable Modular Design. SLP's exclusive three-piece modular design makes it possible to easily upgrade to SLP's Long-Tube Headers without the need of purchasing a brand new X-Pipe by just removing the down pipes. This unique modular design also makes it easy to install this X-Pipe on your Mustang with just basic hand tools.

Quality Stainless Steel Construction. Constructed entirely from 2.5" mandrel bent stainless steel tubing for improved exhaust flow, this SLP Mid Pipe features a true "X" crossover, not a poor-flowing clam shell imitation that other companies use. The included SLP High flow cats far out perform the restrictive stock catalytic converters to increase rear wheel horsepower and torque.

Application. This Catted X-Pipe from SLP is designed to be a direct bolt-on for the 1999-2004 GT, 2001 Bullitt, 2003-2004 Mach 1, and 1999-2004 SVT Cobra Mustangs with either aftermarket short tube headers or the stock manifolds and a dual catback exhaust installed.

Technical note: 2004 SOHC and DOHC applications require the use of 18" O2 sensor plug-in extender wires.

Fitment: 1999 2000 2001 2002 2003 2004 Details

What's in the Box
Hardware included:
  • (4) 2.5" band clamps
  • All required fastners (nuts, bolts, washers)
  • Flange gasket
Installation Info
Tech Specs
Mid Pipe Specifications
Style Mid Pipe: Standard/Shorty length "X" Type Headers Required: Shorty/Long Tube
Piping Material: Stainless Steel Piping Size: 2.5"
Catalytic Converter: "Yes" Fitment: 1999-2004 GT, Bullitt, Mach 1, and Cobra Mustangs.
Will it fit my Mustang?
  • Bullitt - 01
  • Mach 1 - 03, 04
  • Cobra - 99, 01, 03, 04
  • GT - 99, 00, 01, 02, 03, 04

Fits GT, Mach 1, Bullitt, and Cobra

People Who Bought This Item Also Bought

Most Helpful Reviews

SLP Super "BOLD"

Checked all the products offered for mid-pipes, After rechecking each one for their reviews I decided to go with SLP. Bassani had the cat cutouts , The price for the difference was not me. I made the ...

Read More
Helpful (11)

Good product, but!!!

I bought the SLP xpipe with catback power flo and is a good product but my stang is dropped 1.5". The problem with this xpipe is that too lower that original hpipe. I ran two since and if I have two adults ...

Read More
Helpful (11)

Overall Rating 4.5 out of 5 stars
Read All 91 Reviews

Customer Photos (17) Submit Your Photo

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11 Questions / 6 Answers

Ask a Question

Are the downpipes compatible with BBK 1-5/8 in. Chrome Shorty Headers for a v6 mustang?


  • This Catted X-Pipe from SLP is designed to be a direct bolt-on for the 1999-2004 GT only and will not work with the V6 models due to different piping size.


Helpful (0)

Will this fit a 2003 Cobra? Will this also bolt onto some borla stingers?


  • The SLP Catted X-Pipe is designed to fit all V8 Mustangs from 1999-2004, including the 2003 Cobra.

    Rob D

Helpful (0)

I plan on installing a duel exhaust on my 04 v6 mustang and was wondering if these will work with the stock headers my car already has. Choice of exhaust is slp loudmouth.


Is this catted x pipe carb certified? because i live in CA and if its not then are there any catted x pipes that are certified?


  • This midpipe is not CARB certified and cannot be used in California.


Helpful (0)

I have this x-pipe installed on my 03 GT already. Will SLP long tube headers work with this x-pipe? I assume the extra tubes right after the cats can be removed and you can hook up the LTH?


  • This x-pipe will be able to work with SLP long tube headers because of the aforementioned tubes. Those can be taken off and the long tube headers can clamp directly up to the position of the catalytic converters.


Helpful (0)

Is this CA Emissions legal?


  • This is a tough one. The catted x pipe should pass the sniffer test during emissions, the bigger issue is the visual inspection. You would need to find a place that only does the sniffer test. Might be easier to just move to another state.


Show 1 more answer Helpful (0)

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Customer Reviews (91) Write a Review

Overall Rating 4.5

out of 5 stars

Installation Time:Full Day

Installation Cost:$100-$250

  • Loudness / Volume 4.341464 4.3
  • Exhaust Note 4.487805 4.5
  • Fit & Finish 4.073171 4.1
  • Bang For Your Buck 4.121951 4.1

  • 3/5

    May 25, 2011

    Good product, but!!!

    I bought the SLP xpipe with catback power flo and is a good product but my stang is dropped 1.5". The problem with this xpipe is that too lower that original hpipe. I ran two since and if I have two adults in car, is problematic. Around at 2000rpm had a loud drone tone. I dont like the sound at 2000rpm. above and over is awesome. But if you dropped mustang, think twice before buy this SLP system. The SLP compagnie, said the xpipe is builted for a stang with lot of power and torque. So he said you dont wont the xpipe to hang under the car. He said your problem is your car dropped. So I project to take off this system and I think I will go with Bassani. Hey AM, Under this puschase you should write a big attention for next buyer. I spent over 1200$ and I'm desappointed. I lost my money.


    Year: 2003 Submodel: GT

    Helpful (11)

  • 5/5

    July 04, 2010

    SLP Super "BOLD"

    Checked all the products offered for mid-pipes, After rechecking each one for their reviews I decided to go with SLP. Bassani had the cat cutouts , The price for the difference was not me. I made the right choice, This SLP with ceramic cats sound very good from idle up Flowmasters Delta Flow 40s behind them provide the tone, throttle response improved Installation was 1hour 30 minutes perfect fit first time!!! No leaks, Thanks for speedy shipment.


    Helpful (11)

  • 5/5

    August 29, 2009

    Great Job!

    Put these on with an SLP LM-1 cat-back and its definitely worth the money. The highflow cats improve flow greatly as well as a deeper tone. The greater opening in the cross over section is also a great power gain. Must get this if you want to really do your exhaust right.

    Justin B

    Helpful (9)

  • 4/5

    May 16, 2010

    Pypes to SLP

    I went the cheap way and put the Pypes x-pipe on about a year or so ago! It sounded wicked!! But it was way to raspy at certain RPM's. I just put this SLP X-pipe on with my Loud Mouth 2's and it sounds soooooo much better it has that mustang tone and its not raspy at all! It was a pain in the But to have to remove the studs on the driversiade because it comes with two new blots but it was well worth it! I should have bought theese the first time!!


    Helpful (6)

  • 2/5

    May 03, 2010

    SLP X Pipe

    I purchased and installed this product in my 2003 Mustang Cobra. I've always like SLP products and currently running SLP LM1's as a cat back. The fitment for this x pipe was horrible on the cobra. I had the pipe installed by a local shop and noticed it leaked near the header. After a few weeks, I took the pipe to another place that had to weld/fix the part that connected to the header as the flange didn't sit right. As an added kick, the pipe hangs WAY low. I can actually see over the exhaust pipe. A few mechanics have told me that the pipe was junk and to get another one. As for sound, its great. I did run the same pipe on a 03 GT and the fitment was great, not sure why it doesn't fit the cobra right. Will be purchasing another x-pipe from another


    Year: 2003 Submodel: GT

    Helpful (6)

  • 5/5

    October 06, 2010

    04 COBRA

    pair with original 40's you would've thought i had a cobra by the sound truly sounds like a demon is coming out of the tailpipes lol


    Year: 2004

    Helpful (5)

  • 5/5

    May 03, 2009

    Automatic \'03 Stang

    Just like the comment below mine, I started off with the LM2\'s. Then now with the SLP X pipe. When I woke up my Stang and everytime I wake up my Stang, I get this beautiful deep roar. The install was just as easy installing the catback. The only problem I had was removing the two studs on the driver\'s side header. The shipping was free and super fast! (3 days). Thanks American Muscle!!

    Christian E.

    Year: 2003

    Helpful (5)

  • 4/5

    April 01, 2011


    I started off with LM1's and stok H, was getting 25.5 mpg on the highway... put this X w/cats on and (Although the throttle response and power was better)my highway mileage went down to 22-23 ish... if it's performance with mileage for a daily driver that you are looking for you're gonna need a tune if its more than a cat back that you wanna do, get a tuner to make it work for you the whole way, not just accidental horsepower. This ia a good kit, nice build quality and fitment, but trust me, the tune is necessary to make the difference from better to best.

    Mark Dittrick

    Year: 2000 Submodel: GT

    Helpful (4)

  • 5/5

    March 23, 2011

    SLP Catted X-Pipe

    I bought this x-pipe put it in an now the mid pipe rubs on the ground. The actual piping hangs down further then the stock pipe. Im now having to replace the left side cat because it has been destroyed. This is all from normal day to day driving. keep this in mind if your car is already lowered.

    Anthony Cooley

    Year: 2000 Submodel: GT

    Helpful (4)

  • 5/5

    July 01, 2011

    slp catted x pipe 03 gt

    Good price. Cannot give you a comment on the sound quality due to the fact that the drivers side flange to the header does no4 even come close to fitting. Even after using a rubber donut to make it sit more flush it has a very annoying leak.....


    Year: 2003 Submodel: GT

    Helpful (3)

  • 4/5

    June 09, 2011

    SLP "X" pipe

    It took 1.5 hours to remove factory mid pipe off the exhaust manifolds. Ford uses stainless nuts & bolts , heating with torch didn't help much! Once they were removed, SLP X PIPE, bolted on in 20 minutes!! Installer has his own exhaust shop for 26 years! My Mach 1 has a deeper more noticeable grumble at idle and roar accelerating!!!! No back pressure at all!!


    Year: 2003 Submodel: Mach 1

    Helpful (3)

  • 1/5

    June 05, 2010


    I had the exact same problems as Pat. Fitment was terrible. Was on an 01 Bullitt. Took off after a year of struggles. Flange didn't sit right. Cats hung extremely low. So low it dented on a bump and I had to replace it. And it hung crooked, one side higher than another. I've had 2 catbacks from SLP which I've loved, but this was such a headache I will never buy SLP again, regardless how good their tips look. And 2 sets of MIL Elims never fixed the CEL. FWIW, it did sound awesome when I got on it.


    Year: 2001

    Helpful (3)

  • 5/5

    Installation Time: Afternoon

    March 04, 2013

    Perfect Combo!!!

    Just got thru installing these bad boys along with a Flowmaster American Thunder (stainless version, AM part #18436) on my '02 GT, and I couldn't be happier. I'm 32 years old, so the days of being obnoxiously loud have come and gone. This set up is great. There's no real "drone" until you hit about 85 mph, and even then, it's not bad at all. The combo is fairly mild when you're not getting heavy on the skinny pedal... But when you do - everyone around you will know it. Great fit and finish, everything bolted up exactly like it should have. I've used cheaper products on other cars in the past, and it's very true that you get what you pay for. I had originally planned on getting the BBK catted X-pipe, but they were out of stock when I ordered. No regrets at all about spending the extra money on these instead! Great set up, couldn't be happier!


    Year: 2002 Submodel: GT Cypress, TX

    Helpful (2)

  • 4/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    May 10, 2012

    SLP X-Pipe

    Just got these installed and they sound awesome! It gives my stang that real raspy racecar style sound. I have this x-pipe along with my MagnaFlow catback, but it is no where near as loud as people are making it out to be. Don't get me wrong, it sounds great, it just doesn't bring that ground rattling rumble I was expecting. The new cats alson hang down a lot lower than the old ones (about an inch#, so be careful with speed bumps; especially if your car is lowered. Me and three buddies attempted to install ourselves, it is a lot harder than you'd think. The bolts on the exhaust manifold are near impossible to get off. Had a shop do the install for $200. So I was in it $660 #I had to get the O2 extensions). Overall I'm a happy customer, but $660 is WAY to much for the outcome. But as always American Muscle is the absolute best!


    Year: 2004 Submodel: GT VA

    Helpful (2)

  • 5/5

    June 06, 2011

    Awesome system, may require welding

    After extensive research, I decided to go with the SLP catted X-Pipe to replace my factory H. I had a reputable local shop put the pipe on and it ended up having a leak which I also heard a lot of people complain about in forums. My leaks were coming from the front of the cats where they connect to the down pipes. The shop owner told me that even though the bands that SLP provide are nice equipment, they were leaking due a slight off angle in the front down pipes at the connection point. He suggested welding them in the front and it would eliminate the leak and it did. I didn't mind that it needed to be welded as I wanted the catted system in the first place. I would recommend having a shop who is familiar with working on Mustangs install this for you as it can become super frustrating if it doesn't line up right or if there is a leak somewhere. As for sound, I love it!!!! It gave the car the exact added sound I was looking for coupled up to a Flowmaster 40 series cat back. Sounds the same for the most part at idle but you instantly notice the difference while rowing through the gears. There is no rasp/drone at all which is a plus with the catted system. It gave the car a much deeper muscular tone throughout the power band, especially between the 2k-4k rpm points, no CEL either which is great. I couldn't be more pleased with the system or with American Muscle!!!!!!


    Year: 2002 Submodel: GT

    Helpful (2)

  • 5/5

    February 18, 2011

    X pipe

    Product was shipped on time and came with everything needed yo install i took old h pipe off but could not remove manifold stud i recommend taking to a mechanic to have installed i ended up haveing to take it to them to get studs heated luckily i live right next to shop


    Helpful (2)

  • 5/5

    July 20, 2009


    Best X-Pipe Also Fits on V6... it says it doesnt but it does. My Car Roars like a v8!!


    Helpful (2)

  • 5/5

    February 20, 2008

    SLP X-Pipe

    Great product, Sounds great with my flowmaster 40\'s!


    Helpful (2)

  • 2/5

    Installation Time: Full Day

    August 28, 2012

    poor fit

    The SLP catted X pipe was made with such poor fit that it would not seal properly to the left manifold . it had to be fitted with an extra piece of metal to seal to the exhaust manifold .


    Year: 2001 Submodel: GT

    Helpful (1)

    • Response from AmericanMuscle

      Sorry to hear the fitment of this x-pipe wasn't perfect on your '01 GT, but glad you were able to complete the install. I'm sending your feedback over to SLP so they can look into this and ensure it doesn't happen in the future. Thank you for submitting your review and helping us provide the best products that we can!

      Lisa , Customer Care

  • 5/5

    July 16, 2009

    Want to hear the sound?

    I've got a comparison vid on youtube between the stock H pipe + SLP LM2 and this X pipe + SLP LM2. Just look up FILIPINOTUNER. Check it out, you won't regeret it!!


    Helpful (1)

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