I've noticed in my Z is that the Stillen intercoolers allow not so much a performance increase, but rather CONSISTENT performance regardless of how hot it is that day. However, I think humidity is something else and it does rob power! I must admit, the IC's did get rid of a very light spark knock at 15psi so I didn't have to back off the timing. One thing- HKS claims something like a 20hp(!) gain with their IC's. Was HKS the way to go?