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 2.5" vs 3" with exhaust cutouts question
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Civilian
Tribal Scout

19 Posts

Posted - 26 Nov 2016 :  11:51:50 AM  Show Profile  Reply with Quote
I'm going to buy Electric exhaust cut outs from QuickTime performance. The collectors of my long tube manifolds are 2 1/2 inches, but will accept 2.25 inch to 3 inch. Currently, I have 3 inch pipes that are about 2 feet long. My question is, would you run a 3 inch exhaust all the way back, utilizing 3" cut outs, or would you go with a 2 1/2 inch since the collector is 2.5" anyway? Am I gaining anything by going with the 3 inch? Whatever I choose, 2.5 inch or 3 inch will then be continued all the way back as well.

Admin
Ye Olde Webmaster

848 Posts

Posted - 26 Nov 2016 :  9:40:00 PM  Show Profile  Reply with Quote
Unless your engine is pushing 450 hp or better, there is no loss using 2.50" exhaust pipes.

"Dedicated to keeping the classic Pontiac engine alive."

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cortcomp
Coyote

USA
5338 Posts

Posted - 26 Nov 2016 :  10:01:47 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Make sure they're not the ones with the plastic gears in the housing...Bear ran into that here, the gears melted.
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Civilian
Tribal Scout

19 Posts

Posted - 27 Nov 2016 :  12:56:43 PM  Show Profile  Reply with Quote
The car should be right around 500 hp at the crank. I won't be racing it or anything, just want to be able to scare the hell out of people. Do either of those facts change your answer at all? Am I going to see enough sound/performance increase with the 3 inch to make it worthwhile? I will definitely have to cut reliefs in the transmission crossmember for the 3 inch, possibly the 2.5 inch as well.
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frankie
Buffalo

USA
62 Posts

Posted - 27 Nov 2016 :  2:34:54 PM  Show Profile  Reply with Quote
IMO I would go with 3 inch as the sound is fantastic and check out this site about the different in horsepower and torque. MOTOR TREND The Power of 2.5/ vs. 3-Inch Exhaust /Engine Masters Ep. 9 it sounds like you have what I may have in my car, 400 stroked

https://www.bing.com/videos/search?q=you+tube+3in+vs+2+1%2f2+exhaust&view=detail&mid=BFC55330036CB8B30A1BBFC55330036CB8B30A1B&FORM=VIRE
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