Replacing 2-1/2" system w. 3" ... is it worth it?
 

I had a mandrel bent 2-1/2" system with H pipe and Goerlich Accelerator mufflers done 2 years ago. I was thinking I would enjoy the lower db of the mufflers and H pipe. Now I am regretting it and want to go back to the chamber Thrush mufflers I used to run and take out the H pipe. The car lost that "cammy" idle sound it used to have without the H pipe.

The Goerlich's are longer cases so I am probably going to have to have new mid-pipes fabricated anyway to avoid looking like a patched together mess underneath and so am considering just hanging a complete 3" system under it and being done with it. Local muffler shop charges $125 for complete R&R and a system from summit is around $300.

My 2-1/2 system with the Thrush chambered mufflers was pretty wicked sounding. How much louder/obnoxious will a 3" system be as compared to the 2-1/2"? Should I expect any performance gains out of +/- 400HP 455?

Let me know your experiences with this kind of upgrade.

I don't think you will see any performance gain with a 3" exhaust at your power level. You need to be above 550 Hp for a 3"system so it will be a matter of sound what you choose.

I picked up 2/10’s plus by switching from 2 1/2 to 3 inch exhaust off on my 2 1/2 RamAir manifolds. Both exhaust systems were mandrel bent with x-pipe , dual mufflers and tail pipes . My motor is approximately 450 HP

Did you make any other changes??

I picked up the 3" summit kit with mufflers for my '72 Camaro. If it's loud/nasty you're looking for, this is where it's at. I haven't taken it out for a longer drive yet so I can't really say about drone or anything. I went from a 3 1/2" glasspack that exited just in front of the back tires, so I actually quieted things down a bit.

I changed out the front 15x7 Rally II's with 255/60-15's with 15x6 with 205/75/15'.

Nothing Else, I will post some Time Slips tonight or tommorrow when I'm at home.

With all these different brands of chambered mufflers...............are they any different in sound that a typical Flowmaster mufflers? I' had a pair of Super 44's (3" with X-pipe))on my t/a with healthy cam and really didn't care for the tone, kind of docile compared to Flowmaster 40's and H-pipe on my old SD455 with HO-Racing cam.

MANY years ago I put on Flowmaster mufflers, to me personally they had a 'tiny' sound I did not care for. Although not a chambered design since then I've only used DynoMax Ultra Flo Welded or the Super Turbo and never looked back. That said, everyone has personal preference.

Related- a "H-pipe" crossover and "X-pipe" crossover sound much different.

http://www.dynomax.com/mufflers


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There are different videos out there comparing different brands. But often they may not be apple-to-apples testing since some changes may have been made. Like adding a X-pipe with the change. Or going from 2-1/2" exhaust to 3" with the change.

Here is one Flowmaster vs Dynomax video........

https://www.youtube.com/watch?v=0o3QTdNYLBw


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I'm a dynomax fan, as they have produced much less drone issue and a more refined sound in everything I've used them on.

Even with that said I still have one car with flowmaster super 40's.

As for exhaust pipe size comparisons, I did that very thing on my chevelle many years back.

Started with a complete 2 1/2" flowmaster kit, with an "H" cross over and mandrel bends and flowmaster mufflers with Flowmaster 2 1/2" tail pipes. Car was stuck in the 12-teens at 112 mph.

I switched to a 3" system, with a Dr. Gas "X", still Flowmasters but in 3", and 3" torque tech tailpipes. Basically a 1/2" larger system. Right off the bat with no other changes it clicked off 11.70's at 116 mph and I eventually widdled that down to mid 11's at 118 mph and that's pretty much how the car still sits today.

Sometime I would like to install some dynomax mufflers on the car if I ever get around to it just because I prefer the more mellow sound of them, and if I want to make noise or simply bypass the whole system at the track I'll just open the electric cutouts.

2.5" pipes into 3" Flowmasters, into 2.25" tailpipes

vs.

3" pipes with H, into 3" Borla ProXS, into 3" mandrel tailpipes.

7.8:1 455, unported heads, Tri-Y headers, Performer intake, Q-jet (metering rods changed to optimize both configurations), custom low-lift 222/242 116lsa cam.