I've got a JDM tune on my GT (w/ PP). Car has GT350 intake manifold and throttle body, Stainless Works H-pipe catback exhaust (will soon have SS headers as well). JDM tune was the first to successfully and reliably work with the GT350 IM & TB. The car is fast and reliable, I track it at least once monthly and have had ZERO issues.
EDIT - oooops, didn't realize I was in the V6 corner here - but my comments on JDM tunes still stand. They are very good.
Larry from the v6 section runs our nitrous tunes on his 15 3.7 and has been working great for him.
If ou have any questions you can contact me via pm or phone