Flowmaster 40 - JeepForum.com
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post #1 of 6 Old 09-10-2013, 02:40 PM Thread Starter
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Flowmaster 40

I recently purchased a flowmaster 40 off of Craigslist. It looks great and I ant wait to get it on. It is a dual exhaust and I didn't want to make mine a dual. I was wondering if there is a way to change the muffler into a single instead of dual. Will there be back pressure problems?

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post #2 of 6 Old 09-10-2013, 07:16 PM
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Chase0808, I will probably get torn apart for this answer but I did the same thing on my YJ. My muffler rusted off and the day I cut it off a friend gave me a flowmaster 40 that he cut off of his truck. Being broke and in need of a muffler I welded it on. The length was almost the same as stock but the inlet and out tubes on the 40 were considerably larger. I just pie cut the muffler openings and reduced them down then welded the pies up then welded the muffler on. Then I just welded a plate over the second opening and off I went. As far as the backpressure goes I am not an expert but I will tell you I have run it that way for around 6 or 7 years and haven't noticed any problems. It looks kind of back woods redneck, but I was in a hard spot and I did it for the cost of a couple feet of welding wire, besides looks (especially underneath) don't make my jeep perform any different. I just used what I had to get it back on the road, plus it sounds better than the stock muffler and everyone knows sound adds horsepower right?
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post #3 of 6 Old 09-11-2013, 04:52 AM
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my flowmaster sounds great too. no idea on anything about it because it was hanging underneath and not hooked up when i bought the jeep but a local shop welded it up nice and pretty and its been that way for years now. cover the opening like mentioned above and ride

I don't feel like working on anything at this time so i sold my yj.
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post #4 of 6 Old 09-11-2013, 06:45 AM
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Originally Posted by SoNova View Post
...and everyone knows sound adds horsepower right?
Same principle as swag stickers....

Originally Posted by 14Sport View Post
Until you know exactly what is underneath the, well, not really sure what to call them...mistakes...it's hard to come up with a plan of action.
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post #5 of 6 Old 09-11-2013, 09:08 AM Thread Starter
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Would I be able to use something like this to turn the dual exhaust into a single without negatively affecting anything?

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post #6 of 6 Old 09-11-2013, 10:07 AM
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you could as long as you can get the inlets/outlets in a size to match your current pipe & muffler

only potential problem I see is that USUALLY that type of pipe is intended as a traditional Y-pipe... 2 pipes going in and a single outlet. in that case, the outlet is usually the same size (or more likely larger) than each of the inlets.... your situation I imagine would be reversed.

check Summit or Jegs for the best selection of sizes on that

Good luck

Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
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