Inliners International Forums General Discussion Engines Exhaust size effect - is bigger always better?

I have 302 GMC with a mild cam and reworked head -about 200hp.

The inline 6 is really two 3 cyl. engines whish run better with separate exhausts. Exhaust size depends on cylinder size, hp. and rpm range which produces exhaust gas flow volume.

My best running exhaust has been dual headers with 1.5" on the single port and 1.625" on the dual port both merging into 1.75" header output flanges and exhaust pipes. Stole many pieces and ideas from a double OH cam Jaguar XJ6.