I want to tune my G37 coupe. I've been told that chips and stuff don't work, but is this true? Has anyone done a tune on their car that gave them noticeable results? Which one? I looked at the one on Stillen and watched a video for it, only increased the car by like 5 hp and 5 torque for $400 and that isn't worth it.

 

Check the forum threads. There are plenty of write ups of tunes that have been done on G37's.