The tuning is awesome!
I didn't find any bugs yet, but there's one small problem which you should try to fix. When I have damaged the IS300, provided with the test, the rear bumper which I selected and applied to the car was damaged too. IMO, it should not be damaged, because if the mod is used for a tuning shop mod, or something like that, I'm sure players won't like to get damaged tuning parts on their cars.
I know that there's the Pay N spray for a reason, but it would be stupid to go to there first if someone wants to tune his car.
And one question: Will performance tuning be enabled somehow? I mean, is there a way to implement it, or use let's say, three different settings for each car, which could be the stock car handling, and two other handling settings, specified in the XML?
Sorry if I'm getting annoying with my ideas. You are doing a great job mate.