Ive used both types on my race boats and unfortunately, changing from 7/8" to 1" header and tuned pipe was also associated with an engine switch so I cant fully attest to the performance increases of the exhaust only. Im hoping someone can shed some light on the subject.
Reason I ask: Im building a new race cat and I want to use the BH Hansen drop header to keep the exhaust inside the hull for a lower center of gravity. Ive also had good results with the CC racing 1" Powermaster exhaust. All other things equal, would a BH Hansen 7/8" system with a 2" band pipe vs a CC Racing 1" Monster pipe yield noticeable performance differences?