I have a similar set up to you although the bike is an 04 TBA. Last week I decided to do some work on the carbs, so I spoke with the chap at Jenks Bolts. He suggested pulling all snorkels out (mine has 2 inside the box) going for Thruxton needles and 120 main jets. I have long TOR pipes AI gone and a K&N filter. Like you I did not want to hack up the box although I may do in the future. Anyway after dropping the bowls off I found I already had 120's in so just put the needles in with no shims and took her for a spin. Firstly the bike was a good bit noisier but a nice roar and the power increase was very noticable especially at full throttle. No flat spots good colour on the plugs and a bit of lovely popping on overrun when warm. So I am well pleased and will just leave it as it is. Hope this helps...I think the main difference is the Thruxton needles. I never touched the mixture screw as it seems fine.
