The collector box in the exhaust is to provide a larger volume exhaust pulse, increasing low end torque, which the little 750 kinda needed. Removing it, ala swapping 3rd gen exhaust for 4th gen exhaust, gave you freer flowing exhaust, sacrificing low end for top HP. If you're racing, that can be good. For the street, maybe not so good. Besides, when you do that, you lose center stand capability, a good thing to have to me. Your GBP, your choice. Larry
It also increased back pressure at high rpms, meaning the engine would tend to run a tad lean, but made up for it by allowing some un burnt gases to have a second go at being burnt. Sort of a poor mans egr system. The net effect is as above, at lower rpms the engine would scavenge the cylinder better thus helping make more low end torque. At high rpms it would help slow the flow and prevent over scavenging. Thus making better top end hp. If you swap to another exhaust you change the engines dynamics. This includes fuel usage. Be prepared to do some tuning to get the most power for least fuel consumption.
