Imi-step - For my Kawasaki 779 setup (Factory Pipe, Jetinetics flywheel, SXR prop) and my single Mikuni 46, I use 2.3 needle and seat, 115 gram spring, 120 low and 165 high for the jets. 1 1/4 turn out on low and 1 1/4 - 1 1/2 out on high for tuning. This is from Art at Jetworks. Don't know if this will work for you, but may be a start.
Runs great, I was curious on how it would run on an SXR. You say you love it, is there any noticeable difference from the duel setup?