Digging this up from the grave. I'm curious if the OP or any other member that has installed the Stillen UD pulley has had any issues at all? Where there significant improvements, driveabaility issues, etc.? I had a lightweight under drive pulley on my Acura for over 100k miles and never had one issue and I want every bolt on mod I can put on my G. This and headers are all I can think of. Once I have all the mods I can put on the car I'll tune it with Uprev Osiris tune and dyno it for the hell of it. I don't really care about the numbers, just the feel of the car.

 

my biggest issue is I had this on my G35 and the A/C would not work when at idle. There was not enough of something. The same thing with heat. It screwed around with something. Not sure if same issues with G37, but you did mention something about it in the first post. Would like to know for sure.

 

Updates?