You may be able to switch insurance companies even before renewal, to one that is more mod-friendly. Most will give you a proportion of your premium back if you cancel (phone and ask if that's an option, and if so how much you'll get back, so you can see if it's worth it). Sky Insurance are a trader on here and are very mod-friendly (e.g. they insure them like-for-like).
As for the exhaust, what sort of thing are you looking for ? Something subtle or something loud ? Just something that looks nice ?