I'm using the Dana Marine EX-0054 Flapper Carriage mounted just inside the tailpipes with a rubber external flapper and it seems to work fine however the boat is a 42 staggered 525's.

Tractor pipes?

Yup, I have removed the stainless flappers and I am planning to put the rubber flappers back on instead but I'm also wondering if I can run without any external flappers to let the water exit without anything holding it back..

I already have those on my center engine pipes and I'm experiencing some reversion there too. Not as bad as the rear two motors, but its there. Also, they won't work on the rear tailpipes because the swedge goes all the way to the end of the pipe to keep it dry to right before where it exits.

I ran 3 seasons without any flappers on my exhaust, but I do have factory Corsa mufflers and they have a built in flapper at the muffler inlet. No reversion and I also have switchable exhaust. I recently hollowed out the mufflers and put on the stainless flappers you are talking about. Have used them for 15+ hrs with no issues. When I did install them I had to machine a fix on all of them for a hard to open and close issue, they should move with no drag. Once installed the clamp put too much pressure on the hinge and the tolerance was too tight. I opened up the hinge mating area and that was the fix. It just doesn't seem that the stainless flaps are your issue, you had reversion before the stainless flaps [ATTACH=CONFIG]546455[/ATTACH][ATTACH=CONFIG]546456[/ATTACH][ATTACH=CONFIG]546457[/ATTACH]

Here's another thing then if you don't mind drilling a hole in your pipes and welding on them. Have a 1/2 or 3/4 NPT coupling or bung welded into each tailpipe as close to the transom as possible and connect a hose and dump some water overboard. You could add a valve to regulate how much is dumped. It's going to be louder but I think it would solve your problem and it's not a huge undertaking.

Do you use a steep ramp? Possible your starting it on the trailer while tips are submerged?

HI 5 .............must be those full race cams

I had similar issues with opening/closing of the SS flappers as well when I first installed them and did something similar to ensure smooth operation, so I know that it is not binding up. I had reversion before the stainless flappers but that was what the new full length tails were supposed to solve. The water is dumping less than inch from the end of the pipe. I just don't understand how that water is creeping all the way back up there..

Nope. My boat is travel lifted off / on the trailer every time the boat is launched. Don't use a ramp at all.