Pipe science is over-rated IMHO. Not that correct piping doesn't yield performance, but that the science doesn't always lead to the best solution. Back in the '70s I had a 125 Penton ISDT that we wanted to flat track. Bought a commercial low pipe that was suppised to be awesome, and a friend gave me one he had hanging around. Then I took the stock high pipe, made one cut, rotated to low pipe and a friend welded that up. Everyone said it would never work. Had it dyno'd and the crappy reweld pipe was best by far (jetting adjusted for each pipe). I had done it just to have a spare pipe, not for performance. It was much sharper power band, but for short tracks was great. So, don't worry too much about the pipe.