Does anyone know what the diameter of the down pipe is that connects to the exhaust manifold for a 455? I bought a down pipe with a 2.5" diameter and it seems like I'm having a hard time fitting it and getting it not to leak. Not sure why. Is there some sort of reducer or inlet that should go between the manifold and the down pipes? I know they sell a lot of stuff for racing, but my 455 isn't really a racing car per se, I just want one to work with it. Thanks.
Original pipe diameter was 2-1/8". I have had success getting 2-1/2" down pipe to seal by flaring smaller diameter pipe, and cutting of the flare for use as an insert in the larger diameter down pipe.
