best way to get power at low revs is through engine capacity - bigger really is better. this is not cost effective on a cossie, better to go for a 24v v6.

on a yb, you can raise the compression ratio or go for a supercharger or maybe a twin turbo setup.

unless you really want to splash out on it, i would'nt recommend any of these ideas. best bet would be to buy 2 cossie's, 1 mint one for everyday, and one with a knackered engine that you could swap for a 24v v6 from a scorpio for the rare occasions when you tow.