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

Item 23008
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      Product Information

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


      • 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

      MPN# M31032

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (100+)

      Write a Review

      Ratings Summary

      4.5 out of 5 overall rating from 100+ customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • March 09, 2020

        5 2001 GT - Robaknut Installation Time: Afternoon

        Nice quality.

        2 cats are better than 4. No noticeable power gains but is for sure louder. Can't hurt for flow. Getting the old detached from the manifolds will be a bear after 20 years so be prepared.

        Helpful (0)
      • February 01, 2020

        5 2004 Mach 1 - JoeG Installation Time: Shop Install Installation Cost: $250-$500

        Fantastic Product

        This product required a little more work to install than I was planning, but what a difference. I immediately noticed better throttle response and the sound improvement with my Borla Cat Back set up is incredible. Definitely worth it.

        Helpful (2)
      • January 23, 2020

        3 2002 GT - Jon Installation Time: Less than 1 Hour

        Decent X pipe

        I would say say but your own exhaust clamps to reduce exhaust leak

        Helpful (1)
      • June 05, 2019

        5 2004 GT - Charlest Installation Time: Less than 1 Hour

        Alp cated x pipe

        Great product fits great sounds amazing would recomend to anyone

        Helpful (4)
      • May 05, 2019

        2 2002 GT - MBlaze Installation Time: Full Day


        Got this xpipe kit last March, and have owned it for about over a year. Pro's: sounds pretty good Cons: terrible fitment, Leaks like crazy no matter how much you adjust it, it hangs stupid low to the ground, was a pain to hook up to the headers, oh and the cats that come on it will not let you pass emmisions. So now I gotta spend a few hundred freedom bucks to get bigger cats welded to the system. Thanks SLP for putting cats on the system even though it'll cause you not to pass inspection.

        Helpful (6)
      • November 01, 2018

        2 2000 GT - Josh Installation Time: Full Day

        Great sound, awful fit

        The sound is awesome. I have it paired with the loudmouth and it just sounds like pure race car. BUT the fitment is awful. The cats sit super low. The pipe coming off the headers could have an inch or two shaved off and it would fit much better. Also the fitment to the header manifold on the driver side is horrendous. I will probably be changing this out for the Bassani X-pipe very soon.

        Helpful (6)
      • June 21, 2018

        5 2003 GT - AndrewO Installation Time: Afternoon

        2003 Mustang GT

        Yes the right side cat hangs quite low, but it has given my car a perfect sounding exhaust!

        Helpful (6)
      • May 21, 2018

        3 2000 GT - terry1 Installation Time: Full Day

        Stang gt

        Even though you guys sent me the wrong catalytic converter(s), you did make up for it and overnight me the correct ones. Once they installed the entire exhaust system, I was very pleased with the sound of the x-pipe with the borla s-type exhaust.

        Helpful (7)
      • April 19, 2018

        5 2003 Mach 1 - TimF Installation Time: Full Day

        X pipe

        Awesome kit little bit of a pain to do the passenger side manifold studs but after some words with the car lots of free all and bunch of sockets and swivels it’s on sounds great

        Helpful (6)
      • April 04, 2018

        5 2003 Cobra - ChrisK Installation Time: Afternoon

        SLP catted X-Pipe

        Great X pipe! Easy install just takes time to adjust the Length of exhaust to fit perfectly. Awesome sound and quality welds and clamps.

        Helpful (6)

      Questions & Answers (17 answers)

      5 Top Rated Questions

      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.

      Helpful (5) Show 1 more answer

      If I get this catted xpipe and get the extensions .....I won't have check engine light right? I have a 2001 gt

      If I get this catted xpipe and get the extensions .....I won't have check engine light right?

      • You will not experience a check engine light with this mid-pipe.

      Helpful (0)

      Will this work with the Flowmaster series 40 catback?

      Is it necessary to have long tube headers with this for an 01 gt?

      • Unfortunately this x-pipe will not work with long tubes. You would need shorty headers or the stock manifolds.

      Helpful (0)
      Post Your Question
      10 More Questions
      Is this legal in New York Long Island? 1 answer
      Do the cats just bolt on? If so, can you replace them with just piping? 1 answer
      Are the downpipes compatible with BBK 1-5/8 in. Chrome Shorty Headers for a v6 mustang? 1 answer
      Will this fit a 2003 Cobra? Will this also bolt onto some borla stingers? 1 answer
      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. 1 answer
      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? 1 answer
      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? 1 answer
      I just have SLP LM1 catback on my 03 GT right now, but switching from stock H to this SLP catted X-pipe what HP gains will I see? 2 answers
      Does this slp x-pipe fit the 4r70w automatic cars 1 answer
      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? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      Hardware included:
      • (4) 2.5" band clamps
      • All required fastners (nuts, bolts, washers)
      • Flange gasket

      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
      • Cobra - 99, 01, 03, 04
      • GT - 99, 00, 01, 02, 03, 04
      • Mach 1 - 03, 04

      Fits GT, Mach 1, Bullitt, and Cobra

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