Young Performance

That was my video that you saw. I am absolutely not convinced that the lack of a flapper caused it, unless you took a roller up the pipe or backed it into the water to quickly. Under normal circumstances, the lack of a flapper will not cause reversion. The pre 07 headers are known to leak, especially if they have ever been overheated. We pressure test the headers of EVERY 525 that comes into the shop, and that's probably 20+ a year. Any leak in the header will cause the water to be introduced earlier into the exhaust then it normally would. Because of the size of the cam, it sucks the water right back into the cylinder head. From there, it runs into the combustion chamber, past the pistons and rings, and into the oil pan. They are right on the verge of pulling water back in when the water is introduced into the tailpipe where it normally should be. So you can imagine that if the water enters the exhaust earlier than normal, it will suck it right back in.

Reversion will only happen at idle. It will not happen while you are running down the lake. At that point, there is enough pressure in the exhaust to push any water out. The only way you can be sure that isn't happening is to either pressure test the headers (should be done yearly) or let it idle, without ever revving it up, for about 10 min and then lay the headers back and look for water in them or milk in the oil.

We pressure test the headers with the garden hose using about 50 psi of water pressure. We cap off the outlet on the collector and hook the hose up to the distribution tube, turn on the hose and look for water. If there is a leak, it will piss water everywhere. No mistaking it.
Eddie