Personally, I think the underdrive pulleys do nothing, and as for the tune, it just pushes the parameters to the max so you get everything bit of HP...now, what you didn't mention, which has proven to help, is a CAI...cold air intake...go to www.needswings.com and view what Rob sells...or better yet, talk to him....good luck...but, keep in mind, these cars were discontinued, therefore, there aren't a lot of aftermarket parts for them...