hi guys

for a TwinTurbo 350z how much can we go in whp with a 2.5 exhaust with down pipes and dumps.

i askd this cuz i wana know what is best for street car with a built engine.

2.5 or 3 inch

thanks

 

I have an AAM 2.5 and i made 513 hp and over 550 ft lbs tq. I say 3 inch for 550 plus maybe 600.

 

(I say 3 inch for 550 plus maybe 600.)

+1

 

i have run both 2.5" and 3" on my car, both exhausts designed exactly the same and same mufflers. i noticed a touch better throttle responce with the 2.5" system in the lower rpms (4000 and below) at lower throttle inputs (40% and below). but, the 3" felt better all around. your dumps though will help quite abit once you reach boost. the tests were done in the same day also.
all of this is based off of fairily normal street driving. my vote is for the 3".

 

overZealous1. ok so ... what about if some one have a 2.5 dwon pipes with dumps + a 3 inch catback exhaust ???

is this set up good or bad ? i mean do i have to make it complete 3 inch from the dwon pipes to the exhaust ???

 

well, sounds like i would need to test your set up. your exhaust typically is only as good as your smallest point. yet, like a venturi effect, it just depends on where it is at and how long the constriction is. 2.5" test pipes going into 3" duals w/ dumps should keep ya in a pretty good streetable range.

all i can say is, when i tested my 2.5" system against my 3" system on my car. the 2.5" won 30% of the votes, and the 3" won the rest. this was on normal street driving also. my exhaust design is quite abit different than others though.
bottom line, you might be leaving a few horses at the table, but not a bad set up.

 

+1 i have 3" on mine. aiming 600 whp

 

overZealous1. this is my setup

ultimate racing 2.5 dwon pipes with dumps + APS 3 inchs exhaust.

turbos are twin turbonetics T3 STG III and the wastgate are HKS

im still wating for my sleeved block, its with todd at builtzmotors. i miss my car

 

I have the borla TD right now with some 2 1/4 test pipes. Think I could use this for a 500rwhp setup?

 

If you look at what it is CAPABLE of flowing, the answer is yes. HOWEVER, chances are that your turbo respose would suck.