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Pypes 2.50-Inch Stainless Steel Replacement Flow Tube Kit (79-04 All, Excluding 03-04 Cobra)

Item 20109
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      Review & Installation Video

      The Pypes 2.5-inch stainless steel replacement flow tube kit fits '79 to '04 V8 and V6 Mustangs, and '94 to '99 Cobras. You're gonna wanna check out a kit like this if you're upgrading your exhaust in stages by buying a mid-pipe and then buying a set of mufflers, in whatever order, instead of picking up a cat-back. A cat-back comes with these flow tubes, which are located between the mid-pipe and the mufflers, but if you pick up just a set of mufflers instead of a cat-back, you're looking at needing to reuse your stock flow tubes or picking up these Pypes flow tubes if you wanted to create a full aftermarket system from the mid-pipe back. The install for these isn't difficult. It's a one-out-of-three wrenches on the difficulty meter, and you can plan on spending an hour or two on the install. Sitting between the mid-pipe and the mufflers are the flow tubes. Unless you pick up a cat-back, you aren't getting a new set of these. They don't come with new aftermarket mufflers or mid-pipes, and a lot of people want to be consistent with their exhaust. That means not reusing the stock flow tubes. These flow tubes are 2.5-inch, mandrel-bent, 409 stainless steel. And I'll always say this when it comes to exhaust, but stainless steel's going to be your best bet if you want materials that are gonna hold up and not corrode. Compared to aluminized tubing, any stainless steel's gonna be stronger with a longer life. If you compare 409 to 304 grade stainless, 304's gonna be the top-of-the-line material. 409 stainless is still stainless steel, and it isn't a bad material by any means. You still get the longer life and the protection, but 409 usually costs a little bit less than 304. Speaking of cost, you can expect to pay right about $60 for these. These are currently the only flow tubes that you can pick up on the site, so there isn't really anything that we compare them to, but you know that they're 2.5-inch, and they're stainless steel, and they will fit with any setup. When it comes to the install, this is gonna be a one-out-of-three wrenches on the difficulty meter. You can plan on spending an hour or two, tops, on the install. You'll need a socket set and a way to get the car in the air. Depending on what else you're installing with these, the install might change slightly. If you're just installing the flow tubes and nothing else, the install will be straightforward. Your mufflers should have four clamps on them. You'll remove the two front clamps after unbolting the front flow tubes from the mid-pipe. Remove the flow tubes and swap in your new ones. Clamp them to the muffler, and then to the mid-pipe. I would leave things loose until you have them all lined up, and then tighten them down. And that's gonna wrap things up for the Pypes stainless steel replacement flow tube kit for '79 to '04 V8s and V6s, and '94 to '99 Cobras. You can check them out more online, right here at

      Product Information

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


      • Required for Aftermarket Muffler Installs
      • Mandrel-Bent Construction
      • 2.5" 409 Stainless Steel Tubing
      • Fits 1979 to 2004 Mustangs


      Replacement Flow Tubes. Replacing the restrictive stock mufflers is a great idea, but you may end up damaging the factory flow tubes in the process. That is why we offer Pypes 2.5" Stainless Steel Replacement Flow Tube Kit. This kit will replace the piping between the Mid Pipe and the mufflers for a perfect installation.

      Durable Stainless Steel Construction. Pypes uses sturdy 16 gauge 409 stainless steel mandrel bent 2.5" tubing with a ball and socket-style connector for improved flow and includes a set of two 2.5" 304 stainless steel flanges.

      Application. This Pypes 2.5" Replacement Flow Tube Kit is designed for use on the 1979 to 2004 Mustangs when replacing the stock mufflers with aftermarket mufflers or resonators.

      Fitment: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Details

      MPN# PFF10K

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (82)

      Write a Review

      Ratings Summary

      4.6 out of 5 overall rating from 82 customers

      • February 10, 2020

        5 2002 GT - SimpleMan


        Great product,well , heavy duty. Made changing the mufflers much faster and easy. thank you American Muscle.

        Helpful (0)
      • January 19, 2020

        4 2001 Bullitt - Lgrimm17


        Great fit. Just the right length and diameter and bolts right up. Definitely would recommend for any gt

        Helpful (0)
      • January 05, 2020

        5 1994 GT - Jlee

        Must have

        Product fit perfectly and gave me the extension I needed! Thanks A.M!

        Helpful (0)
      • September 23, 2019

        5 2001 GT - TonyG

        Perfect Fit

        These are a must if replacing your mufflers. Great quality and more importantly the right length. I installed with Flowmaster Super 44’s and worked out great.

        Helpful (0)
      • June 17, 2019

        5 1991 GT - Foxbodylife

        Go with the FLOW!

        Great quality flow tubes with a great discount price. Can’t wait to install these with my SVE X-pipe, BBK headers, flow master mufflers and new flow master tail pipes. Now my new exhaust build is complete for my drop top pony. Thanks American Muscle.

        Helpful (0)
      • April 05, 2019

        5 1984 Other - MiguelC


        Perfect fit, a cat back system isn't really available for a 84, so had to get part from different spots to make one. These pipes were cut and bend to the right length. Very well made, going to order another set to fix my dad's car.

        Helpful (0)
      • March 25, 2019

        4 1991 LX - DonaldH

        Flow tubes

        I would have given this 5 stars but had a little trouble getting these to seat right on my H pipe. The flanges came in backwards. If you install just as they come in, in my case anyway, they end up causing and exhaust leak as they dont sit right on the h pipe ball joint. Reversing the flanges is how you get it to sit correctly. Again may have just been in my case but something to look at prior to install. Other great and work perfectly.

        Helpful (1)
      • March 19, 2019

        5 2004 Mach 1 - Rush

        Pypes Flow Tube Kit

        They fit as expected. Good if you want to build your own cat-back exhaust for a SN95 Mustang using any brand of muffler and existing tail pipes. Or use as dump system.

        Helpful (0)
      • March 11, 2019

        5 1997 GT - RichardK

        Flow tubes

        They seem to work great with the Pypes M80's. But I just had them put on a few hours ago.

        Helpful (0)
      • March 07, 2019

        2 1992 LX - Stickshift5oh

        Flow tubes

        Flanges hit driveshaft and fuel lines no matter how they are hung either ground clearance issues or chassis clearance

        Helpful (0)

      Questions & Answers (14 answers)

      5 Top Rated Questions

      lost the oem nuts to bolt back together, help with size of nut?

      I have pacesetter long tubes and pacesetter x pipe will these fit to connect them?

      Will these fit in place of the mufflers if they are cut out with a stock H-pipe?

      • This kit will replace the piping between the mid pipe and the mufflers

      Helpful (0)

      Does this just make it look cleaner after doing a muffler swap? Does it do anything else?

      • The Pypes 2.5 in. Stainless Steel Replacement Flow Tube Kit is designed to replace rotted flow tubes, or to use in custom exhaust setups.

      Helpful (0)

      I need to know what the bolt hole spread is ? On my headers the spread is 3 1/2 inches . It is 2 1/2 pipe . Is the flow tube , from the header back ? Is the flange spread the same?

      • From center to center of this flange will be approximately 4-1/4".

      Helpful (0)
      Post Your Question
      9 More Questions
      I need to know what the bolt hole spread is ? On my headers the spread is 3 1/2 inches . It is 2 1/2 pipe . Is the flow tube , from the header back ? 1 answer
      Do I have to buy these if I'm buying an x pipe and flowmaster mufflers 1 answer
      Do these bolt on directly to the bracket after the cats? 1 answer
      Will the m- 80 pypes mufflers slip into each end of the flow tube? That way I could just clamp them or will they not fit into each other and require welding? 1 answer
      Where can I find the bolts that go along with this piece? 1 answer
      can you use these to replace where the catalytic covers were welded on? or can i use any kind of straight pipe for that? 1 answer
      x pipe h pipe do these replacement pipes fit for both x pipes and h pipes or r they specific to a set up? 1 answer
      Lenght What is the length of these pipes? i want to make sure they will bridge the gap from my h pipe to mufflers 1 answer
      3 inch mufflers Are these ok to flair to accept 3" flowmaster 10 series 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) Flow Tubes
      • (2) Brackets

      Tech Specs

      Will It Fit My Mustang

      • Bullitt - 01
      • Cobra - 93, 94, 95, 96, 97, 98, 99, 00, 01
      • Cobra R - 93, 95, 00
      • GT - 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04
      • LX - 87, 88, 89, 90, 91, 92, 93
      • Mach 1 - 03, 04
      • Other - 79, 80, 81, 82, 83, 84, 85, 86
      • V6 - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04

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