I'll chime in on the trapps... I pulled my trapps last week with the intention of replacing them with flappers. Needless to say, the seals for the trapps were the original from the factory and they had not sealed the screws that held the flange in. Pulled the screws and had some water come out. Allowed it to dry out as best I could while I figured out how to change over to the flappers. Took five hours but I am happy to report that the exhaust is totally sealed up now and I appear to have fixed a leak that was causing my boat to list to starboard and be heavy in the stern. I know I have a cap off restoration in my future but I feel that installing the flappers has potentially bought me another season or two as I am now limited in water exposure due to a leaking trapp. Oh yeah, I used 4200 back there as well.
'86 Comp TS6M
Riding Connelly Skis and Hyperlite Boards
Rarely ballasted with up to 1500 pounds of ballast