RE: pipe resistance
You are going to want to check to see if your pipe and manifold set up are sealed up and not letting water in the exhaust system somewhere. To do this just pull the hose loose from the pickup (rudder) if that's where it's at and plug the outlet (where the water goes out) with your finger. Blow thru the hose and if it is sealed up no air will escape, This is what you want. If air escapes then you have a leak at the exhast flange or around the pipe orings which seal around the header. Wet coming out of the pipe might mean water is leaking somewhere in your set up... This is always agood practice to get used to and should be checked always to make sure there is no exhaust/water problems. Simple thing to do..
Good luck and hope I explained it so you can check it out yourself.