The cylinder head and intake/exhaust port contour on any stovebolt engine is the choke point. There's simply no way to get an effective improvement in gas flow by improving carburetion or exhaust with that head in the middle. It's like joining two pieces of heavy tow chain with a paper clip. Fancy carburetor(s) and/or exhaust systems are like making a silk purse out of a sow's ear- - - - -it makes the pig look funny, and it doesn't hear very well afterwards!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!