Originally Posted by Arnold K.

Err...I've personally witnessed cars at Performance Motorsport put 320-350WHP (G35 HRs, G37s, 370Zs, and G37 Coupes). One of our 370 members Romulus has a similar mod list as me (exhaust, ART Pipes, tune), and put down 350WHP. He can chime in and confirm those numbers.

I'm not going to waste time digging for dynos. Those of us who hang out at shops weekly and see the dynos for ourselves know what we see and we know the mods. You have a 350Z HR. I have numerous local friends from My350Z who put down those 300WHP+ numbers with stock cats. That's not at all unusual for VQ35HRs at all - just a few months ago I saw a bolt on + tune VQ35HR G35x (that's AWD) put down 315WHP.

I understand you're trying to be conservative, but these motors (especially the 37HR) are very responsive to bolt-ons, much more than you think.