there is so much conflicting info and opinions on this, when senna kindly made one from bits I had last year I lost 6bhp, seems 2-1-2 works bset on a Ducati and most twins, altho the weight saving may offset the cpl bhp it adds...altho there are some 2-1 that are bang on the limit so who knows...
if it helps, I'm going thru the same. New bike has 2 high level cans and I know they will get in the way. SO choice is different link pipes and reposition them, or 2-1 and get it custom made
problem I have is I can neither do it myself nor have anyone local - every place recommended is miles away and even looking thru yellow pages its still 50+ miles to anyone who can do it