Pretty much any reg! Actaully, the stock mini reg is crap, that would be the first thing I upgrade if I got a new lcd. Go with the Gladiator reg made by Macdev, supa high flow.
They're good, but they don't really have the recharge rate needed for an angel (or a cocker with a badass trigger). If you've already dropped a good amount of $$ on a LCD, you might as well get a gladiator.
Well living in the states I would have no idea where to get one, but the go for about $75 US. Try eclipse, they have almost everything, even though they don't put **** on their site
There are a few other choices to that work well. I would definately check out the new Messiah from Air America, the AKA Sidewinder, PMI pure energy (nice and cheap), and Hyperflow inline. So many regs, so little time....