+1 for mlm pipes being meh. Not only are they kind of made generically for bike to bike without much change in design other than fitament, but also they arent made for any specific cylinder. For example; stock magnum peoples pipe, it really sucks on a stock magnum. What are they doing over there? Also I think they use too thick of gauge steel. I know most road racing pipes are 20 or 22 gauge and I think mlm uses 16 and 18.
I would try a simo if someone has one laying around. The black gun isn't great on 74cc, its also discontinued, and if you hack up a perfectly good French is pipe I'll cry. It has close dims to a 6p, but for whatever reason it doesnt want to over rev as much. Ive only ever gotten to 57mph at +13k, cant run tall gears here in Seattle.