jayhawk,
I've worked through e-mails with several guy's this summer to help them set up their kdx's with "alternate" needles in their stock carb's. One was a stock 220 with a k-35 pipe and 33mm carb. I sent him a few needles to try and his favorites were the BEM#3 and for what he refered to as "rock crawling" an AEN#4. I didn't send a BEN so he didn't try that setup. The other bikes were 200's with stock motors and carbs and most of them prefered the BEM for smoothness or with the k-35 pipe and CEM's with the k-30's and pro circuit pipes, although one guy prefered a CEL. These were all run with #5 slides although I did lend one guy my #6 and #7 slides and his favorite setup did end up real close to what most are running with their RB carbs, a 40p/CEK#3/155 main with the #7 slide. I did also have him try a couple of triple taper needles but he found that they were to rich at 1/4 throttle and would load up pretty easy which is much the same results that I had with them. The modified (ported) bikes seem to like a bit richer setup and usually end up with a step richer (straight section) needle than non ported bikes.
Mac,
Have you tried any D taper needles in your 225? I would think that this would be a good choice for your bike as they seem to work well with more aggressive motor setups. A DEL,DDL,DEM,DDM might be worth a try. I have run a DDK in my 200 and it ran really strong although it is better for more open area's as it did produce quite a hit when the power came on.
Good luck and be sure to report back with your result's. There is still plenty of testing to be done and it all help's.
--Dan