I am not real verse on my mopar right now just getting back into owning a wonderful mopar product. I love my 1965 Plymouth Belvede 2 . It has a 440 with a HP exhaust manifold out of a 1968 to 1970 not sure of the year. It has 2 1/4 exhaust pipe now, this is a two fold question. Can it take a 2 1/2 exhaust pipe from the manifold out ? Plus will this help in the performance of the engine?

PS thanks so much guys I am the nut who posted the door lock locking when you pulled it up and opening when pushing it down. Fixed it thanks to you guys . Rod was on the wrong side of the levers fulcrum.

Those manifolds origionaly had 2 1/2" pipe to the muffler then 2 1/4" out.