I hate to be to one to give up power for simplicity, but the K&N filter sounds like a NIGHTMARE for the small gains it will produce! I'm used to building Bbig block Ford engines and usually the more cam, compression, carb, air and exhaust I can bolt on, the better it is! I've only been working on bikes seriously for about 3 years and this is some complicated $h1t! The thought of getting this race built 900 tuned is looking like a seriously daunting task, much less pushing a few more hp out of my old 600...

 

I'm running a K&N with a stock can/headers, no problem. I think the problems start
more when changing the exhaust then the air-filter. Most of the complaints I see,
crop up when the user already has an after-market exhaust and then goes for the K&N.

I had a dead spot in the band between 4000 RPM and about 5500 RPM.
My bike came with a D&D with a 4>2>1 header (without the cross-pipes between
1-2 and 3-4) and the K&N, with stock jetting. When I went back to the stock
exhaust/headers, even with the K&N & stock jets, the 4-5k dead spot went away.

Whether I'm making more or less HP with the K&N vs OEM filter, I don't know.
However, the bike runs fine and I have no complaints with it set-up that way.

Ern