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

77 Reviews
Our Price


  • Item #23008
  • MPN# M31032

  • Market Price $454.95
  • You Save 4% ($18.00)
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Customer Photos
  • 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

Most Helpful Reviews

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 ...

Read More
Helpful (9)

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 (10)

Read All 77 Reviews
Overall Rating 4.5 out of 5 stars

Customer Photos (14) View All Photos

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4 Questions / 3 Answers

Ask a Question

X-Pipe with SLP Long Tube Headers and Glass Pack Tips? I already have glasspack tips on my mustang, but if I were to install the SLP longtube headers with the SLP Catted X-Pipe, could the glasspack tips still be reused?

DRAY93 Year: 2004 Model: GT

  • This X-pipe has an exclusive 3-piece modular design, which makes it possible to install Shorty Headers or Long Tubes. If installing with the Long Tubes, you would just not use the down pipes and then attach it to your catback. Your glasspack tips should not affect the installation of these at all. Hope this helps!

    LisaS Year: 1992 Model: GT

    Good Answer (0)

Question Resolved


STANG33 Year: 2003 Model: Mach 1

  • This SLP X-pipe had a modular 3-piece design that will allow you to upgrade to SLP Long Tube Headers without purchasing a new shorty mid-pipe. General rule of thumb with SLP products, we've found it rare that they directly bolt up to another manufacturer and we recommend only using SLP LTHs with SLP mid-pipes to ensure a perfect fit. If you tried using this mid-pipe along with MAC Long Tubes, it's not a guarantee for direct fit and there may be some modifications necessary for installation. Hope this helps!

    LisaS Year: 1992 Model: GT

    Good Answer (0)

Question Resolved

Engine light and 02 sensors If I install this on my 2003 mach 1 will the high flowing cats cause my check engine light to come on and should my 02 sensors reach or will I need extensions?

DarkGreyMach1 Year: 2003 Model: Mach 1

  • I installed these on my 03 mach 1, replacing all stock items and everything matched up just fine and no check engine light. You shouldn't have any issues

    bankerz Year: 2003 Model: Mach 1

    Good Answer (0)

Answer This Question I need this answered (0) (0)

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Customer Reviews (77) Write a Review

Overall Rating 4.5

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Loudness / Volume 4.296296 4.3
  • Exhaust Note 4.481482 4.5
  • Fit & Finish 3.962963 4.0
  • Bang For Your Buck 4.037037 4.0

  • 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) (0)

  • 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 (10) (1)

  • 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 Driving Style: Daily Driver

    Helpful (5) (0)

  • 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) (0)

  • 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 Model: GT Driving Style: Daily Driver

    Helpful (4) (0)

  • 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 Model: GT Driving Style: Daily Driver

    Helpful (3) (0)

  • 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 Model: Mach 1 Driving Style: Daily Driver

    Helpful (3) (0)

  • 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 Model: GT Driving Style: Daily Driver

    Helpful (3) (0)

  • 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)

  • 5/5

    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 Model: GT Driving Style: Daily Driver 'Stangs I have owned: 1 Cypress, TX

    Helpful (1) (0)