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3" piping to 2.5" AB?

Discussion in 'SVT Shelby GT500' started by 12boss302, Sep 7, 2017.

  1. 12boss302

    12boss302 Active Member Established Member

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    I feel like I already know the answer to this but just wanted some clarification from people that are more knowledgeable than me. I'm running 1 7/8 headers with 3" piping all the way back. I just installed JBA axlebacks but didn't realize that they are 2.5" instead of 3". I was running the MBRP and that was stupid loud and obnoxious so I went with JBA to get a more chambered muffler. The guy welded it just fine but I'm "worried" that sincenits bot 3" all the way back, that "something" might happen. Given all I've done is add a small bit of back pressure to just the muffler, this shouldn't be anything to be concerned about correct? The car is more tame now and I can actually drive with the windows down now, which I haven't done in who knows how long haha. What you guys think? Thanks in advance for your replies and suggestions.
     
  2. Willie

    Willie Well-Known Member Established Member

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    Well, that just depends on you. Many years ago, I added Stainless Works chambered mufflers in front of the axle to my 3-inch system. Then I found out that even though these mufflers have a 3-inch inlet and outlet, the core is 2-1/2". The car sounded awesome, but this fact bothered me..... for years..... Sound familiar? I lived with it until I found a 3-inch core chambered muffler. So I changed them out. I sleep better nowadays!!!

    If you are as anal as me (I am an engineer) and it grates at you, change it. If you are okay with it, leave it as it sounds like you are happy with the sound.

    Performance wise, adding a 2-1/2" "restriction" to a 100 percent 3-inch system will cost you some performance loss.

    It's your call....
     
  3. 12boss302

    12boss302 Active Member Established Member

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    What did you end up getting that's 3"? And is it honestly going to be that big of a difference in performance even though it's just a muffler? That small bit of backpressure can't do too much harm I'd assume.
     
  4. Willie

    Willie Well-Known Member Established Member

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    No, having one smaller restriction in an otherwise 3-inch system's performance loss will be very minimal. Not even noticeable...

    My exhaust is completely custom, except the stock manifolds. I tap into the manifolds with 3-inch mandrel bent piping, a pair of Bassani cats, a Bassani x-pipe (the best design), then a pair of 3-inch chambered mufflers, over the axle to a pair of 3-inch resonators (in the stock muffler location) and a pair of "no-label" 4-inch tips.

    Vegas, huh?
     
  5. 12boss302

    12boss302 Active Member Established Member

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    I understand. I'll see we what it's like here in the next month or so and go from there. I do like the fact that my car doesn't sound too much like a boat anymore. I can post before and after in anyone is interested that is thinking about going along the same path. And yes, Vegas is where the boat resides.
     
  6. Harry08

    Harry08 Active Member Established Member

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    About 7 or 8 years ago Justin from VMP posted on this very topic. I believe he said thru his testing the loss was very minimal and really a non factor performance wise.
     
  7. biminiLX

    biminiLX never stock Established Member

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    I have 2" ARH headers to 3.5" collectors to SW full 3" pipes and just welded stock mufflers back in. I think they neck back down to 2.75" but the system was still good for 964rwhp, so it's not worth stressing on the power, as the restriction at the farthest point means the least. Go for sound not power on the mufflers IMO.
    -J
     

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