Hello all, I'm currently having a 500hp + engine built for my 1989 Formula 242. I'm going to cut the baffles out and was wondering if I could leave the rubber flapper's off the exhaust tips? The butterfly flappers are gone that used to be in the transom. I moore the boat in the summer and wonder if water will back flow easily without any stoppers. I found new easy install 4" exhaust flappers I might buy just for safety. Any input?

If your tips are straight out the stern, I wouldn't remove the flappers. If you have to stop quick, there would be some major water headed up the tubes.

What kind of exhaust you using?

Coming off plane and backing off the trailer could be a problem. I also would leave the flappers.

It's got the silent thunder exhaust coming through swim platform. I'll be using older style merc blue 420hp performance manifolds.