In my testing I get the best results with 2.9V, right now I am running my new Kingston at 219 doing 2-2-2-11 on NF2.
Some people report that it can go well above 220 with 3.2V. I am just not ready to try, the improvement I get going from 2.9 to 3.0 V is very marginal, perhap 1 FSB, just not worth the chance of damaging memory in a long run.
I had very similar results with Mushkin and Buffalo as well. I am just not successful to go anywhere much higher than 221, which is still awesome. BH-5 rules for the tight timings. 215 sounds about right with 2.8V.