1G 2 1/2 vs 3" exhaust from downpipe

[abakja1]

I have a 90 Mitsu GSX,....I did a engine rebuild (broke TBelt) at 120k miles,....Now when I drive my car, all is strong till 3100rpms and above when my car feels "choked off" and has a hard time revving up to its 6500-7000 redline after 3100k,..

I put in 95 pistons, port heads, and minor mods as air can, KN, Dejon 2 1/2 UIC, wires, and MBC set at 15psi,...Right now I have no cat, but a test pipe a local shop did that seems smaller than the factory pipe size(maybe 2" diamenter in order to weld it in place) and stock pipe size going out to a 2 1/4 inlet N1 type muff,...

Im going to muff shop this week to customize my exhaust and changing my N1 to a 3" inlet type,..Do you think I would be going overboard with a 3" vs 2 1/2 pipe from downpipe to the rear with my mods, and would this help my problem with the car not reving past 3100k easier? The guy is going to charge $120-140 for 2 1/2 size, so going to 3" diameter size a little more at $200 so not much diff,....Would the 3" be too overboard (lose torque or/and power)? Or is 2 1/2 good enough with a 3" inlet N1 muff going out the rear?

Any help needed quickly and very much appreciated,..
abakja1

 

[ItsStockOfficer]

ALWAYS 3 inch and you should go mandrel bent but its alot of money.

As for being choked off, sounds like a bigger prob then exhaust.

Sean

 

[WhipmastaFlex]

depends on your goals. if you're on the stock turbo, 15psi... that is not enough to warrent 3". if you plan on going big16g or larger, FMIC, upwards of 350hp at the crank, etc.... then yes, i would go 3" to save having to swap out an exhaust for an extra 1/2"

 

[Cirus_93TSI]

regardless of ur mods get the 3", it will make more power then a 2.5" on even lightly modded cars, and unless ur planing on keeping ur car slow for the rest of its life u will need a 3" down the line anyway, so instead of buying a 2.5" and deciding ur not happy with it after a few months and spending the money again for a 3" just get the 3" from the get go