Are internal flappers in exhaust tips necessary? I just got new ones that have them but my old ones didn't have them, but they had slip on mufflers on them. I would like the boat to sound as loud as possible. Thanks

Ask yourself this questions, if for some reason you boat stalls while you are on plane and settles back into the water, is there away for water to rush back into the exhaust and into the motor. Because it happen to me and it hydro-locks the motor right up.

You eliminate some risk if you have them, whether coming off plane or the boat sitting anchored. I have a buddy who was anchored at a beach on Lake Ontario with some big rolling waves. Water splashed into both exhausts (no flappers) and hydrolocked both engines when he went to start them. This made me replace my burned out flappers with some "no burn" flappers. They don't hurt anything and they don't take away sound but they take away one more potential problem.

Same thing (waves) happened to me on my first boat a 242 Formula with twin small blocks.

When I redid my exhaust system on my 311 Formula, including dropping the silent thunder box to go with a clean transom and lose weight, I install (from Trick Marine, another shameless plug) Eddie Marine Thunder aluminum manifolds/risers and Stainless Marine Tips with the "superflapper". I don't think it effects the decibel limit at all but it might save an engine. I wouldn't run tips again without them.