I want to mod my Cobra enough to retain the factory warranty and still dust off the former C5/Z06 badazz cars that run around here every year for the annual Ecklers Corvette show. I had some fun with them stock. Now I'm putting on the Bassani X-pipe with the Hi-flow cats and the Catback as well. I'm working on a decision for the CAI to install too. Should have it all here and installed by the end of this month. I've heard that some plugs can boost the performance a little. Are there any with significant improvements over the others that would warrant the money ? Keep in mind, I have to stay within the warranty for now. So any suggestions about any component that will increase my performance would be appreciated greatly. Also, are the plugs on these things difficult to change out? Special tools ? Thanks guys!!