I don't know about letting off the gas, and I have an automatic so your experience might differ, but unless you plan on doing intake and exhaust mods, the tune isn't really worth it. All I did was add a cold air intake, no exhaust, and there's **** near no difference whatsoever. It might have eliminated the throttle lag but I really don't notice a difference, and it's just putting in premium gas for next to nothing. On the other hand, there's a iA FB group and the admin of the group installed the AEM cold air intake, a custom exhaust, a few other small things and with the tune, he was getting 120hp (an increase from 90hp stock) all dyno'ed and everything. He's actively trying to make the iA faster and working closely with someone on a turbo for the engine. So unless you plan on going all in, all you're doing is paying $500 for very little. Again, my experience is with an automatic, no idea about manual.