Yeah, not a bad car. Personally I just threw every possible upgrade at it, and left it at that. I never bother messing around with the settings, except changing the gear ratios for the Test Track races. It handles pretty well with just all the upgrades and no specific tunning, so I'd just leave it like that. Alternatively, have a look in the GT3 tunning forum, I'm sure someone will have a setup for it there.