Littlez

How much flow should be coming out of the tailpioe at idle? The reason I am asking is because I was at the car wash and the bay I was in is sloped making the tailpipe run up hill at the tip.... When I was spraying the back of ny truck I noticed the soapy water was running into my tailpipe with ease... Shouldnt there be enough flow to atleast resist the water water? When I put my hand over the ezhaust I could just barely feel exhaust.