Yup - Blackhorn 209 is the good stuff. Pricey and only available as loose powder, but burns very clean. Also helps aid accuracy by allowing you to fine tune your load instead of having to jump large increments as with powder pellets.
I haven't found a pellet yet that burned very clean. White Hots are fine, but I still found a nasty "crud ring" starting just ahead of the load after only a few shots but I'd still say they are a good choice. And I agree with all others, that 2 pellets is plenty.