I know 3" piping is too big for NA preludes, however my JDM lude came with a 3" bore catback from Japan....
Its probably the sweetest sounding exhaust ive heard, will this 3" bore piping be losing me power over std?...
If so any ideas how many bhp i'll be losing?..

Ive got Intake, VAFC at the moment, + this 3" bore zorst..

 

i didnt know they came with 3" from the factory in japan, or is it aftermarket? the larger the ID of your exhaust the less back pressure you'll have which you want on a NA motor. but then again you have some of the NA racers running open headers. honestly, since its just the cat it should be a huge issue, it will be like having no cat at all since i assume your exhaust piping is smaller then 3".

 

no I meant the exhaust is a 3" cat-back....

The cat is the std JDM one, the exhaust piping is 3"... you see my problem?

How much bhp am I giving away?

 

ohhhhhhh i see your dilemma, i guess i misread your post I didnt know that the stock jdm's came with 3" exhaust??? if its stock, its there for a reason and i would leave it the way it is... are you sure its 3", i know for a fact that there arent any companies that make 3" for the prelude except the one doing the group buy going on right now... as far as hp, im not sure if you are losing or gaining, the only way to know for a FACT is dyno it with the 3" then dyno it again with a 2.5", installing an exhaust doesnt take long at all.

 

Its not a stock JDM exhaust, it was on my JDM lude when it was imported...
Seemed a good quality exhaust, sounds great..

 

was it custom made? i dont know of any companies that make a 3", i just had a custom 3" made last week, how low does it hang?

 

It didnt appear to be custom made...
It was a stainless backbox on a mild steel 3" pipeing, came with resonator, also it is in two sections, one to axle then the backbox.
However soon after I fitted it the baffles in the rear box started rattling, so I cut the rear box off and welded a Kakimoto racing 3" rear box (from a Nissan Skyline) on in place...

The rear box was welded to a high quality and had a straight cut 4" tip

 

Didnt appear to be too detrimental to my BHP figures

Had my VAFC set up on the rollers, made 10.6bhp extra peak

Base run 171 wheel Bhp

after VAFC tuned 182bhp

Car is a JDM spec VTEC