2.5" vs. 3" True Duals
Thread Starter
Teching In
Joined: Apr 2012
Posts: 9
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From: MKE, WISCONSIN
2.5" vs. 3" True Duals Hey all,
I have a 00 SS with bolt ons, pacesetter lt, y-pipe, cutout and dyonmax catback. I am trying to decide between 2.5 tds or 3tds into the cme exhaust...I have searched and found both and mixed! 3 in x into 2.5..3 all the way, 2.5 all the way!!!
Will I get that much of a gain going to 3 or is it all just different sound between the two?
Also if I run duals, will I gain from having cut outs also?
Thanks for the input!
I have a 00 SS with bolt ons, pacesetter lt, y-pipe, cutout and dyonmax catback. I am trying to decide between 2.5 tds or 3tds into the cme exhaust...I have searched and found both and mixed! 3 in x into 2.5..3 all the way, 2.5 all the way!!!
Will I get that much of a gain going to 3 or is it all just different sound between the two?
Also if I run duals, will I gain from having cut outs also?
Thanks for the input!
TECH Fanatic
Joined: Jan 2011
Posts: 1,358
Likes: 0
From: Michigan
3" is just kinda the norm. I sacrifice no clearence with mine. The header collector is the lowest part of my exhaust and I'm under the axle. It might be choking it to the slightest degree but not enough to tell. Though a dyno will say otherwise..and you could get more of a popping sound with the smaller diameter piping. Cut outs imo are pointless when running duals. The hp vs $ for cutouts isn't worth it.
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I have 3" from the collectors and dumped at the axle with Flowtech 3" mufflers. Car still picks up slightly when the cutouts are open.
I don't buy into the 2.5" is big enough camp personally.
I don't buy into the 2.5" is big enough camp personally.
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Same here...if an engine is set to shift at 5500rpms and puts down 500hp peak at 5000 rpms is that going to use the same exhause setup as an engine that shifts at 7000 rpms and peaks at 6500? More rpms means more exhaust to get rid of. LSX motors just don't seem to conform to the tried and true rules in the exhaust world from what I've seen.
A better question is will 3" make more power. To say 2.5" is enough is not the big picture. Yes its enough to make good power but will 3" make more? I say yes. Maybe not much more but if its 5 more hp would you do it? What if you do heads/cam in the future? Then it might give you 10hp or more.
Very well put. It would be interesting if anyone had any actual dyno experience with this. There are probably some guys making good power with an 'I' pipe too LOL.
Your just going to make more hp/trq with the dual 3" over the 2.5"(all else being equal), and the hp/trq spread only grows as you make more power. Now if exhaust space/clearance is a issue then of course the 2.5" pipe have an advantage.
