Welcome to the best Kappa forum, you will find lots of topics about aftermarket parts.
I suggest to do a reading initially and then start posting questions for your particular case.
The things are pretty clear around here about mods.
Tune:
- if you care about your warranty go for GMPP upgrade
- you are willing to go aftermarket there are some good tunes: Westers and Trifecta are most discussed around here. If you have knowledge you can tune it yourself using HP Tuners.
Exhaust:
- only one name and most of the owners agree: Solo Performance
- there are some other options also: RPI, Borla or Magnaflow
If you like twisty roads many will suggest you a ssupension upgrade: coilovers, backbone and probeam, Z0K bars.
You have some homework to do.
