Absolutely right, a 3 into 1 tends to lose out at the top end compared to 3 pipes, but the sled guys have been building them for years and make good power up to 8500 -9000 but hose pipes are huge. Not large, huge. Maybe that's not teh word I 'm looking for. Humongous. Yes that's it.
On a bike it's harder to get a pipe that will work at a large range of throttle and Revs. OMARs which I believe is made by Jon Easton of JEMCO in Texas are supposed to be a nice pipe. If I manage to get one I'll test it over the winter back to back with the JEMCO triple pipes just for fun. Not sure how well it will work with a ported cylinder though.
Seviston,
That bike sounds nice. Jetting (warm) must be pretty good. Well done