yes I knew this from before,but maybe not as detailed. I used to have a rossi 53 with tuned pipe, also I`m into scooter tuning so I understand how a tuned exhaust works, but on this 49 engine I have done as adviced and still no power well i`ll try again tomorrow and se if the added length does the trick or not. according to your posts elsewere on rcu the engine is run in when it can hold its top rpm for a minute and that usually appeares after a relatively short somewath rich 2 stroke run in, so I dont think further run in will show significant increase in performance, so I think its all in the adjusting of the pipe from now on. strangely, reports on this engine wary wildly from realistic 13000 to unbelievable 15000+ on my beloved 12.25 prop. also I find that people say to just press the pipe and header all the way together, and now I know that doesn`t work either. Its just a little frustrating to read all about how fantastic and powerful this engine is and not be able to even get close to the same performance myself. I might add to this that I`ve been into this hobby for quite some time and also race buggys and monstertrucks so I`m used to playing around with glow engines. hopefully the added length in the coupler was the missing link