Horns for Rock.

gotta agree with the heresies. classic hybrid, and rocks

You could also look for some of the pro model La Scalas. Bigger bass driver than stock. They come in a couple varieties (split or full cabinet) and they aren't very common, but can be found. There's also a pro model Heresy - I don't know how or if that speaker differs from the stock model. I have pro La Scalas (full cabinet) and they are all I've ever wanted in a rock speaker, and any other for that matter.

Altec is another speaker you really ought to investigate before making a final decision.

Thanks for all the suggestions, he bought a brand new pair of Klipsch Heresy III's for a really good price.

Another vote for the Klipsh Cornwall II's or LaScalla's. Some of the best rock speakers ever. Did I mention they will play really loud?