All right, so my neighbor wants to upgrade the running gear on his Wal-Mart Hyper dual suspension mountain bike. Standard 21spd 3/7 split. I'm pretty sure the bike has a direct mount RD, which is going to be likely the first point of upgrade-itis. It's got a Crap shimano unmodel derailleur on it now, I think a TX50 or something like that. What I'm wondering is what better derailleurs may for this in the 7spd range with a direct mount? I already told him he'll need to recable and switch to a rapid fire shifter to do this, along with a new chain.

Before you start on the "get a better bike" line of thought, I've gone over this with him. He wants to stick to his hyper, so that's what we're doing. I think sharpening up his shifting, swapping to good tires and tuning it up will make a world of difference.