hmm, i noticed mine does this also. I just got mine on Wednesday and fired it up today. mine was slightly used so break in was done all ready.

I think the best thing is a new pipe. A single chamber to be exact. I believe the stock one is a dual and is for more top end.
Your temps are high by the way. Book says 250 tops. I know that is not all ways true but i like to stick to it.

How is your LSN pinch? I am wondering if your HSN is too lean (causing high temps) and your LSN is too rich(causing it to be bogging). Try the pinch test at a little less than half a tank and it normal running temps and see what you find.

If you are unsure about what the pinch test is let me know. I can help.