jeff350lc runs jetts that are smaller that stock,he has gp pipes and a modilied airbox and stephenrc45 has used smaller than stock jetts on his 250.i dont know much about jetting but i understand what you all mean,one point i have is, by going to larger main jetts,as you go up in sizes at some point you arent going to get enought air in through the carbs even with no air box to atommize(sorry if its spelt wrong)the fuel correct,is this right?if it is i guessing that this must cause a problem to the way the oil is mixed and the way the fuel is burned,so thinking about it if you need to use main jetts the sizes stephen did on his 300 then might it be better to use bigger carbs,this will mean you can draw more air across the main jetts meaning more fuel from smaller main jetts and this will stop the problem of the fuel not atommizing correctly,wont it?and wont it mean that as your burning less fuel the exhaust gas temp will be lower and so with the cylinder pressure,as there is less fuel to compress?