Quote Originally Posted by blueguy View Post
Keeping manifolds gives it the factory low-end torque curve.

Unlike headers...that sure, you might see gains from...but it's up top.

Not as useable on the street.

Magic and straight pipes apply.

I over-guessed a little bit. Not too bad of numbers from a stock pulley/injectors...with a cam/heads/DP. It'll really pick up some power up top IMO when you swap injectors...especially if you said they were running static @ 5100~.

Only thing I wouldn't do again is run a double roller...I killed the gear on mine...probably due to stupid low idle speed....but I'd just run a stock chain + some 130's and a higher idle next round.
What DR did you run?

There is a gain going with 150# springs over 130's on the XPZ...I'm probably no seeing it at this level though.

I'm not real comfortable using 130's on a stock chain. I'm doing it on my 01, but it's not something I'd feel comfortable running for 50k miles without looking at it. I have about 10k miles on the chain in my 01, so we'll see what it looks like when I pull it out in the winter.