I haven't downloaded a whole lot of impulses yet. (Also my recording software is freaking out, so I can't mess with it at the moment) but I Really like using a Matchless 2x12 Left, and Diezel 4x12 Right.
SoundClick artist: Chris Stoffel - page with MP3 music downloads the first song Dead By Dawn(Impulse) first song i've ever recorded with impulses. Thats got the Matchless L, Diezel R going on too.