I posted a "drums and bass only" version of Iron Man way back when on GBT by removing the guitar from the instrumental version, but at the time all vocal extraction attempts i made turned out crap... the other day i finally found a good source to extract the vocals pretty cleanly, so i then synced the vocals to the drums and bass BT... also got rid of the guitar bleed at the start by looping the kick drum, plus did a fade in on the left channel ;-)