| Not sure if this is correct, but I was told that with today's fuels it is not so easy to tell if the fuel/air mixture is right by inspecting the plugs.
The freer flowing exhaust will weaken the mixture which will certainly make it produce more power. Unfortunately, it will also not do the engine much good if there are exceptionally weak spots now. A dyno run would confirm this, and shouldn't cost too much (recently saw cost of about £20 to get a graph done). Cheap compared to the damage that might be done from running too hot.
From my own experience, I recently had to ditch the ECU that came with the Termi and had the standard ECU refitted. I was having a Power COmmander fitted to correct the fuelling, and the initial dyno run showed just how weak the mixture was at the top end with the termi and std fuelling. They were concerned that I had been riding it for long like that, which I hadn't. For waht it's worth, there was no indication that it was wrong from the way it ran, in fact it seemed fantastic.  |