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#1
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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.
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Triple Black 1971 GTO |
#2
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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.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
#3
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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
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74 Formula 469, 6X-4's, 72 Intake, Ramair Manifolds. 3 inch exhaust with x-pipe Custom Roller Cam, 1.52 Roller Rockers Quadrajet done by Cliff 3:42 gears 12.075 @ 112.70 12.092 @ 112.43 12.128 @ 111.71 |
#4
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Did you make any other changes??
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Shawn 1971 Formula #s match white/tan 1973 TA Brewster/white #s match 1972 Buick GS455 #s match 69k miles now a 470 stroker. 1986 Buick Ttype 66K miles many mods 10 sec street car. 2001 Mustang gt premium vert. Mamas car |
#5
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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.
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#6
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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.
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74 Formula 469, 6X-4's, 72 Intake, Ramair Manifolds. 3 inch exhaust with x-pipe Custom Roller Cam, 1.52 Roller Rockers Quadrajet done by Cliff 3:42 gears 12.075 @ 112.70 12.092 @ 112.43 12.128 @ 111.71 |
#7
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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.
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Home of WFO Hyperformance Shaker induction. |
#8
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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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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 06-10-2019 at 11:53 AM. |
#9
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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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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#10
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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. |
#11
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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.
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'73 T/A (clone). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 315rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'. '67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust My webpage http://lnlpd.com/home |
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