DHZ: yeah i used that method to tighten it, im sure the pipe is against the copper ring, and the ring is against the head, i pulled the ring out just then and it's all been squashed evenly, there's a perfect round indentation on both sides where it's sealing. i rekon i'll grab some of that exhaust pipe sealant as well just to make sure, i'll also check for any potential vacuum leaks.
i took it for a spin tonight, doesn't glow while riding, but when i stop it glows a bit. bike feels really good with the oko, took a bit of fiddling around though to get it perfect. initially it was bogging down a bit in the low rpms, but after playing around with the mixtures it's running pretty well. up top in the rev range its running absolutely awesome.
i'll pull the plug out tomorrow and have a suss, and i'll try dropping the e clip a notch, see how that affects it.
thanks heaps for all your responses, it's helping out massively. learning heaps about the bike and how to do a lot of the work on it. all good fun!