[92xjunker]

They flow too well, cv carbs need that restriction in the filter to create a pressure drop on the head side of the carb, this lifts the slide. You can run a K&N filter but, It just doesn't have the same effect as the OEM throughout the entire rpm. The doughnut is a bandaid to the effects of the filter flowing too much.

[tone]

Nice idea 92xjunker & i do see your point but we've been running them here in the uk for years & once setup correctly have no problems in fact a K&N filter & decent exhaust is pretty much the normal setup fo 75% of uk kats & about a million bandits, gsxr's etc etc

Now while some of those bikes dont perform properly (despite what the owners think) a good number of them do so what differances are there on US bikes compared to UK bikes that could cause this ? all i can think of or find is some very oddball jetting on some US bikes & the ones we've had in to sort out all had very poor base settings