I can confirm the results, I was there when it was done and both mine and Yallaairs tachs showed the same readings. The pipe makes this 8cc engine effectively a 14-15 cc engine powerwise. This engine is not a revver OR a torquer, it is both. We have the exact same engine and I have broken the 15K barrier on the APC 12-4 (it is tuned of course, but no pipe was used) It depends on how one set up the engine, it can revv small props or lug big ones.