Mp215 is a subtle but very noticeable improvement over stock. There are better reviews on the forums than I can provide but I love it. The car isn't a rocket but it's so much fun. Mountune will do custom calibrations if you buy an access port from them, but that's not covered under warranty. From what I've been told by Mountune the mp215 is fine to use with the Mountune intercooler and even a cat back. But adding a down pipe will need a custom calibration. They plan on coming out with MR tunes (only the MP tune is out right now) but the MR tunes are not warranty safe.