Did you change the water inside at all? They push a lot of water through the chamber. I want to mod mine with an adjuster like FPP does.Thats what im running on mine. 90 sj with a 701. Seems like an ok pipe. Just rotate the tail cone until you find a position that clears. I have mine with the stinger positioned about 45 degrees up from the floor on the tank side.
You sure the headpipe orfice is that small? My recollection is its way big.The kawi version has a longer tuned length and sticks out farther than the yamaha Sizzler version. A complete Sizzler setup fits and works better on a Yamaha. Dont use a flow valve, just install a bypass pisser between the engine and pipe. The pipe cooling orfice is perfectly sized at .060".