BREAKING: new 4 in 4 exhaust

[Paris_imp]

I'd be interested in a 4 into 2 like on the early 90s 750 Nighthawks. Hmm, a search may be in order...

I saw a huge jump in torque and an extension of the power curve when I replaced the 2 into 2 stock exhaust on an '81 CB750F with a 4 into 1. As I understand it, there is a big advantage using a 4 into 1 over even straight pipes if it is tuned correctly. The exhaust pulses traveling down the header create a vacuum which scavenges more exhaust out of other cylinders.