those exhausts really make that much whp gain?
 

went to dyno with a friend, he only has CBE(with y pipe) changed, other than that his car is all stock. The problem is the hp gain was not even close to what manufacturer claims. That made me wonder those manufacturers claims 18whp or 20whp gains on exhaust are even true(without tuning)? Not trying to make any company looks bad, just wondering cause I am in the market for exhaust myself, thanks.

Ah yes. Marketing departments.
They tend to run numerous dyno passes and record the highest gain. Average gain would be more honest, but it's a case of "mine's bigger than yours".

Not all exhaust systems are going to yield massive results... some are rather poor actually... the Fast intentions seems to have the highest numbers with a full CBE with test pipes getting about 25 or so whp.

I myself would likely go with their exhaust with the Motordyne ART test pipes, their pricey, but they aren't as loud as test pipes, but have gains over all test pipes so far that i've seen... but there could be some out there that do better.

The more expensive exhausts are USUALLY expensive for a reason... they get results.... but that's not a hard and fast rule either.

It also depends on the type of dyno and the temperature as well.

you're doing pretty well if you see half of what they claim.

yeah, good point.

I saw (I believe this is correct) a Z with a FI exhaust and test pipes, G3 intake and Stillen headers make 324 hp at the wheels. I don't know if that's the highest out there for an NA Z, but I haven't seen in anyone's sig more than that... but that doesn't mean it can't be done.

raw numbers mean less than nothing.

I felt a good gain from headers and catback from F.I., no dyno though. With intake and tune put a solid 334whp and 252wftlb

It also ran 317 hp on a dyno dynamics... does that mean nothing also?

When I installed my Berk cbe, I definitely felt the difference on the butt dyno :P

means nothing without a baseline taken immediately prior, and then only the delta matters.

http://i36.photobucket.com/albums/e3...26_4281768.jpg

^ that graph, with a couple of modifications to correction parameters, can yield as low as ~450 whp and as high as ~1000whp.

exhausts are tough because the extra sound always makes you feel faster:tup:

I understand that without a baseline it's hard to tell... however, based on what your average 370 baselines at, those are pretty good numbers.

yeah, but you don't know the oddities with that dyno/conditions unless you run a baseline. I can give you 400 whp on a stock Z if you want it, and you won't be able to tell what I messed with.