Silent Thunder is a non-switchable exhaust that Formula developed years ago. It is a fiberglass box that mounts under the swim platform. If you have switchable exhaust with stainless tips out the back then you do not have Silent Thunder. I only ask as those boxes tend to rattle and vibrate the boat at certain RPM's while coming onto or coming off plane. Regardless, Mentalpause most likely has your solution.

Thanks guys I'll try slower deceleration and see what happens. First twin engine so much to learn.

Enjoy and be safe....