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SLP High Flow Catalytic Converter Kit (96-10 All)

Market Price $199.95 You Save 4% ($8.00)
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  • Item 23034
  • MPN# M31040

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Features, Video & Details

  • Improved Exhaust Flow
  • Universal 2.5" OD and ID Design
  • Stainless Steel Construction
  • Ceramic Substrate Material
  • Will Pass Most Emissions Tests
  • Durable Construction
  • Sold as a Set of Two

Review & Installation Video

Review & Install Video

Hey, guys. Stephanie with, here with the review of the SLP High-Flow Catalytic Converter Kit, from 1996 to 2010 Mustangs. In this video, we're gonna talk about the materials and construction of these cats, and the install as well. I'll talk more about the install shortly, but I can tell you right now, that I'm gonna call this a two out of three wrenches in the difficulty meter because you will need to make modifications to get these installed. You should check out the SLP High-Flow Cats if you're looking for a two-and-a-half inch stainless steel Cat for a naturally aspirated setup because you're trying to abide by emissions laws. But you still wanna ditch the very restrictive factory cats, for something that's gonna open up volume, and a little bit more power from the exhaust. These high flow cats offer a good compromise between staying legal, and still having a great sounding Mustang. You also might wanna check these out if you have an off-road setup on your car currently, but you're looking to tone down the volume or the rasp a little bit. This SLP kit has two Universal, two-and-a-half inch cats that are stainless steel, with an internal ceramic substrate material. This makes these cats perfect for naturally aspirated builds. If you don't have a naturally aspirated setup, I would recommend checking out some of the other options since there is a set of cats with a metallic substrate material, for the force induction carbs. SLP claims that these will pass most emissions tests, but what I would say is that I never promise all high flow cats pass all state emissions tests. That's honestly just the name of the game, and I can't really guarantee something like that, unfortunately. I will say, though, that if you don't feel like swapping out your exhaust when you have your emissions and inspection, then there's no reason not to try these. When it comes to price, you can expect to pay just under $200 for this kit. It's the least expensive option on the site, although the pipes offered for NA cars is only about $25 more. When you're shopping for cats for force induction carbs, the things get a little bit more expensive, because you need a different material inside of the cat to handle a higher exhaust temp for those builds. When it comes to the install, depending on how you install these, you can expect to spend a few hours, and it's gonna be a two out of three wrenches in the difficulty meter because you will need to make some modifications in order to get these installed. What exactly you need to modify will change depending on if you're cutting out old cats and replacing them with these, or if you're adding these to an off-road system. But either way, it's not a terribly difficult install. You're gonna need a good socket set. Something to cut the exhaust with like a Sawzall with a fresh blade, and a jack and jack stands or a lift to get the car in the air. If you're replacing cats with these, you'll already have your location marked for you, and you can proceed. If you're putting these into an off-road system, you need to mark and cut the mid-pipe to make room for the cats. I would then file the pipe down to make it smooth after cutting. The cats do have a specific inlet and outlet side, so you wanna make sure that you have the orientation correct before installing. And you can clamp these into place or weld them in. It's up to you. Wrapping things up here with the SLP High-Flow Catalytic Converter Kit, this is a kit that offers two Universal, two-and-a-half inches stainless steel High-Flow cats, for naturally aspirated applications. These are gonna help you keep your Mustang loud, or help you tone down an off-road setup, and you can check them out more online right here, at

High Flow. Are you looking to free up your restrictive exhaust, but are required to use Catalytic Converters? AmericanMuscle has the answer in the form of SLP's High Flow Ceramic Catalytic Converter Kit.

Durable Construction. These SLP Catalytic Converters are made out of Stainless Steel and a durable Ceramic substrate material making them perfect for naturally aspirated applications.

Will pass most emission tests. SLP's High Flow Ceramic Catalytic Converters will pass most states emissions testing procedures. However, check your local and state ordinances for installation and usage regulations.

Application. This SLP High Flow Catalytic Converter Kit is designed for use with Mustangs from 1996-2010 and is sold as a set of two.

Fitment: 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Details

What's in the Box
  • (2) Catalytic Converters
Installation Info
Tech Specs
Will it fit my Mustang?
  • Bullitt - 01, 08, 09
  • Mach 1 - 03, 04
  • V6 - 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10
  • Cobra - 96, 97, 98, 99, 01, 03, 04
  • GT - 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10
  • GT500 - 07, 08, 09, 10

People Who Bought This Item Also Bought

Most Helpful Reviews

SLP high flows

Overall great product with great customer support. AM price matched it for me and everything. I ended up writing an install guide for the cats in hopes to make the installation for others a bit easier. ...

Read More
Helpful (27)

SLP High Flow Cats

I had these cats welded on to my bbk o/r x pipe and no complaints at all. Top notch SLP quality, makes a non-catted x pipe sound so much better throughout the rpm band, no more rasp with my exhaust and ...

Read More
Helpful (9)

Overall Rating 4.6 out of 5 stars
Read All 41 Reviews

Customer Photos (4) Submit Your Photo

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23 Questions / 5 Answers

Ask a Question

I have a 03 3.8l and right now I'm true duelled with no cats and pypes m80s but as I idle down my exhaust sputters. I went back to the shop and then tell me it's because of lack of back pressure. I've never heard this noise on a mustang before but anyways I'm wondering if these cats will bring up my back pressure enough to fix the sound. I know it's hard to say without hearing the car but I really don't want to spend another $300 for a quieter car that still sputters.. Any info would be appreciated. Thank you


I have an 05 gt stock exhaust my car. Converter died... Will this directly fit or will there be a need for customizing? Secondly I intend to do some upgrades before end of year... All new exhaust new cams intake throttle body.. Will this work with these upgrades or would a different cat work better?


  • Hello! These are designed to be a direct fit for SLP X-pipes only. You will likely need to do some cutting and/or welding to install them. These will work with the upgrades you intend, although a new exhaust may replace these catalytic converters.


Helpful (0)

Will these fit any 2.5" H-pipe regardless of year? I want to make my catless 2016 legal.


  • Hello! You may be able to get these to mount up on a 2016 Mustang but it would likely require cutting and/or welding of the existing exhaust..


Helpful (0)

These catalysts come in pairs or singly, I have a Mustang 06 GT, I have the engine sensor turned on, and when I go to 25 miles per hour, the engine wants to shut down and the mechanics told me that was the catalysts,so I need new catalysts converter, the SLP High Flow Catalytic Converter Kit would work fine


  • There are two catalytic converters included in this kit.


Helpful (0)

can i use these with the borla stinger exhaust system on my v6 with the exhaust adapter. basically what im asking is if i have a v6 and put a exhaust adapter on can i use these, the adapter, and the borla stingers or would they not be compatible


  • If you get the necessary adapter these SLP High Flow Cat will be installable on your exhaust system.


Helpful (0)

Are these California legal?


  • No, California does not like high-flow catalytic converters. All the aftermarket cats we sell are high flow.


Helpful (0)

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Customer Reviews (41) Write a Review

Overall Rating 4.6

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Performance Gain 4.222222 4.2
  • Fit 4.333333 4.3

  • 4/5

    January 11, 2010

    SLP high flows

    Overall great product with great customer support. AM price matched it for me and everything. I ended up writing an install guide for the cats in hopes to make the installation for others a bit easier. Only reason why I gave it 4 stars is because no installation hardware came with the kit. You either need to have them welded in or you need to purchase 4 exhaust clamps. (I bought 4 for $8)

    Andy M.

    Helpful (27)

  • 5/5

    March 31, 2011

    SLP High Flow Cats

    I had these cats welded on to my bbk o/r x pipe and no complaints at all. Top notch SLP quality, makes a non-catted x pipe sound so much better throughout the rpm band, no more rasp with my exhaust and sounds much cleaner


    Year: 2002 Submodel: GT

    Helpful (9)

  • 5/5

    December 29, 2010

    great cats

    I am extremely happy with these high flow cats. I was concerned will losing clearance under my 2008 Mustang, but the size of these cats matched the stock cats. This allowed them to be installed right where they are from the factory. Even though they are not large enough to place the O2 sensors, they can still be mounted just behind them on the pipe. Now I have that high performance, that great sound, and maintain my states requirements, exactly what I was looking for.

    Garry Tossing

    Year: 2008

    Helpful (8)

  • 5/5

    March 31, 2011

    dam good

    this product kills the competition. sounds insane while giving the power of straight pipes


    Year: 2000 Submodel: GT

    Helpful (6)

  • 5/5

    July 28, 2011

    SLP cats

    This things are everything you would expect from SLP. I have them custom welded into a bbk x-pipe with loudmouths and I couldnt be happier with it. they give me the sound and the quality i was looking for


    Year: 2001 Submodel: GT

    Helpful (4)

  • 5/5

    June 30, 2011

    SLP High flow Cats

    I love these cats, they go great with my slp lm1 setup, my exhaust is still as loud as I want, and they fit great too. Would recommend these to anyone who needs Catalytic converters.


    Year: 2003 Submodel: GT

    Helpful (3)

  • 5/5

    April 06, 2011

    SLP Cats

    I added them into my bbk o/r x pipe (long tube headers, Flowmaster 40s) They sound great. Here is the problem My stang has the lowering springs. The drivers side cat has to sit about a inch and a half lower for the tranny linkage than the passenger side This puts them less than 1 1/2 inches off the road. and have scraped them on the road a couple times now. I don't even dare go over a speed bump. I really wish i could keep them they do sound great and I'm not setting off car alarms in the parking lots anymore I am going with the MagnaFlow HiFlow Cats they are a lot smaller in diameter


    Year: 1999 Submodel: GT

    Helpful (3)

  • 1/5

    Installation Time: Afternoon

    October 26, 2016

    Good while they last

    I had bought these for more air flow and better sound. After having them on the car for the last 6 months they've already "clogged" and having problems. I don't use any octane boosters and the car has not had an issue with running rich so I was surprised. I had been told that SLP offers a lifetime warranty on exhaust parts, BUT after contacting them I was rudely told that something must be wrong with my car and that I'm to blame. AND they then stated that cats are not covered under warranty because "no company would do that". I'm extremely disappointed in this product and I'd highly advise going with a different company. For the price, these cats are not worth the head ache they give in the long term.


    Year: 2003 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Afternoon

    October 18, 2016

    works great relatively east to install.

    Recommend welding them in. The C clamps that come with the cats are barley Aquitaine .


    Year: 2002 Submodel: GT

    Helpful (1)

  • 4/5

    July 31, 2016

    Great purchase, be cautious!!

    Let me start by saying these things sound great! Definetly added a little roar to my 3.8. Not to mention, a little power boost is noticed. On the other hand, my engine light popped on and I definetly noticed a reduction in gas mileage. Be Cautious!


    Year: 2002 Submodel: V6

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    March 04, 2016

    Slolz high flow

    Delivered on time and neatly packaged... I was looking for something that wouldn't make my car sound so low and these definitely did the job.. if anything they make my car sound so much better.. definitely recommend if you're looking to keep your car sounding loud..


    Year: 2003 Submodel: V6

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    May 15, 2015


    Great sound, and easy to install with no Eng. Light


    Year: 2008 Submodel: GT Pueblo CO

    Helpful (1)

  • 4/5

    Installation Time: Afternoon

    July 19, 2014

    They might

    I purchased these after the Pypes High Flow cat converters that I had bought on this same website gave out after 6 months of light usage, might of been a faulty cat though, the internals broke. Anyways, I decided to try these and although they might not give your stang that deep growl that the Pypes give , they also don't give that nasty raspiness at the end of the growl that I used to hate. I have these installed with a set of longtube and ford racing dual exhaust , still sounds pretty amazing. A lot of compliments on it. Let's hope these last me a bit longer though.


    Year: 2010 Submodel: V6 El Paso, TX, USA

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    June 26, 2014

    I have low end torque again!

    Bought these to accompany the gutted primaries on my '02 P71, eliminated overly loud exhaust and gave me my low end torque back. Roasted the tires for 5 seconds before the car even came off the line! I plan on throwing an X pipe and a pair of Pypes M80s mufflers on in a couple weeks. Thanks American Muscle!


    Year: 2002 Submodel: Other California, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 27, 2013

    The Sound... THE SOUND

    This is a great product, no only will help you to get a little more HP, but it will as well help you with the sound. I already have SLP LM1 and they sound great with the stock CATs, But still not that off-road sound that I wanted. I bought this specially because of the SLP brand and the reviews. I cannot be more happy with them. The sound is the nearest you can get to an off-road sound (with the SLP LM1 combo) I will upload a Video latter so you can judge for yourself s. The installation requires a 5 inch pipe so it can fit your stock mufflers if you are removing your stock cats. Other than that it took my welder about 20 minutes to have both cats welded.


    Year: 2004 Submodel: GT Las Cruces, NM

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    August 18, 2013

    Fixed my bbk o/r x pipe

    I got these to make my exhaust smell and sound better and to be legal. The bbk o/r x pipe sounded terrible with stock mufflers and smelled worse. It was an easy install with a saws all and clamps with good fitment. It toned down the rasp but is still louder and smells almost stock. I feel a little more power compared to stock exhaust. Recommended!


    Year: 2001 Submodel: GT Carlton, MN, USA

    Helpful (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    May 22, 2013

    very nice size can fit in a really tight area.

    overall it has stopped the cel from flickering on and off once in awhile. legal for myu area.


    Year: 1999 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    March 13, 2012

    SLP Cats

    I have a MAC Catted H-pipe. Found out 2 weeks ago that one of my cats went bad that came with the MAC H-pipe. ordered these SLP cats to Replace the old cats and I have no complaints! (yet i I had the old cats cut out and the new SLP Hi-Flow cats welded in. The sound is still agrressive and Im sure they perform just as well..if not better.. NOTE: SLP says that these cats are made ONLY for fitment with SLP X-pipes. This is not the can pretty much have them welded in in any set up...


    Year: 2002 Submodel: GT Mass

    Helpful (1)

  • 5/5

    June 03, 2011

    SLP highflow cats

    great sound and i no longer have SIX cats robbing my horse power


    Year: 1996 Submodel: GT

    Helpful (1)

  • 5/5

    March 31, 2011

    Great Product

    Easy to install. I had the X-pipe off the car, but then completed the install laying on the ground with the car on jack stands. Still pretty easy considering. Came with detailed instructions. About a 1/2" better clearance than the ones I had on previously (don't know the manufacturer) because these have a flat spot on the bottom. I still took a hit on a speed bump causing a dent, and it held up. No funny sounds indicating it cracked inside. My old one cracked and sounded horrible.


    Year: 1998 Submodel: Cobra

    Helpful (1)

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