Hi welcome, you can start by changing the back box for something like a ninja or h&s backbox then if thats not enough maybe look at going further down the system, not sure if yours has a resonated middle section but you could look at going cat back to release more sound, finally if your still not happy could delete the 2nd cat and go turbo back with a full mashings sports cat middle to backbox. But that will require a map tk get the best results and get rid of your cel light coming on.