I've seen that before, IP.
It might be a great idea for a straight-line racer.
...someone going for top end, but still needing to get off the line...
A shorty xchamber will give biggest boost at top end, and a long one the best torque at bottom end.
Sometimes I wish I had not learned all this stuff the hard way. lol
Way back when I bought a shorty xchamber for my DT-1 trail riding bike cuz it was $10 cheeper than the stoopid looking loong one. Boy did it come on the pipe! lol
Marginal on the bottom end, where I really wanted it...
Best
rc