If you pull the resonator off the standard box it sounds almost identical to an induction kit, stick a K&N panel filter in the standard box with the resonator removed and it will more than likely make more power than an induction kit any way.
Any kind of added protection to the sump will help but once the tin worm starts you have to get every last bit otherwise it will keep returning, its the mega hot cat that does it to the sumps. If you find rust treat it with rust killer before painting it.