GMPP turbo upgrade (otherwise known as GMS1) is nice. I got it for my LNF (cobalt ss) and it was totally worth it. That said, if you don't have warranty left I would probably go with an aftermarket tune instead. There are ones that are better than GMS1. Only I reason I went with GMS1 was for warranty.
Considering that Saturn died in 09. I am not sure even the last Redline off the lot is going to have drivetrain warranty.