ls1 exaust size

[big lux]

Hi im trying to work out what size exaust i should run on my gq now ls1 fitted, im going to run twin system 1 cat and 1 resignator each pipe. Im not shure if i shuld run 2.5inch or 3 inch pipe each side?

[Shadow]

twin 2.5" would be sufficient unless you plan on making ALOT of power

[big lux]

engine has an aftermarket cam, heavy duty valve springs / retainers, slipfire coils, 85mm throttle body, 100hp NOS shot, highflow injectors and fuel rail, adjustable fuel reg, surge tanks 044 pump ect, maffless tune,

would like to see 300 kws at rears.

[Zuri92]

twin 2.5 will do but if you are willing to sacrifice a bit of torque for a bit of power then twin 3 inch will be fine aswell people with supras sometime run 3inch on a na setup, and thats half your engine size with half your rear wheel power at their wheels..... with a cam etc.

[brooksy]

Forget 3" twin, total waste of both power & torque. LS1's lack mid torque & running too big an exhaust just won't work.
I have had 3 LS1's with 2 of them running well over 300kW & have had all of them set-up via a Dyno.
1st was a Statesman & was just a cruiser & numbers were low but economical, 260kW.
I got best torque from a tri-Y 1 5/8" primaries to twin 2 1/4" to 3" single with 320kW.
Other was 4:1 collector with 1 7/8" primaries to twin 2.5" both with mufflers & no resonators at rear with 355kW.
All 3 except Statesman run cold air induction & various fuel injection changes/upgrades with chip & tune.




brooksy

[big lux]

Ok i cant run x pipe or y pipe due to the tranny ect have to be 2 seperate systems. headers im looking at are 1 3/4 runners to 2.5 inch colector from marks 4x4? Why did u go mufflers from what ive been told muffelers make it quietr and reignators make it deeper?

[351ciofgrunt]

Ok i cant run x pipe or y pipe due to the tranny ect have to be 2 seperate systems. headers im looking at are 1 3/4 runners to 2.5 inch colector from marks 4x4? Why did u go mufflers from what ive been told muffelers make it quietr and reignators make it deeper?

Resinators by themselves are usually too loud. There are some nice sounding mufflers out there, like flowmasters.

[JonnoD]

A resonator will not change volume. They are used to eliminate "booming". unless you are happy with a crazy loud truck I woud suggest using atleast one muffler