I recently bought new cmi exaust headers because one was leaking and I bent a valve, now I still see a little water up on the collector , i cant seem to figure a way to pressurize the tail to see if it is leaking, any suggestions??

rubber drain plug..pump it with air to seal off,,use garden hose on other end..

http://www.petersenproducts.com/114-0_pipe_plug.aspx

check home depot