either the evolve bolt kit, or he bolt kit are good... was looking at getting a nox bolt in my old 05. if its compatible, then theyre meant to be the best on the market at the moment, and are apparently selling like hot cakes in the states
killa detents are much better than stock ones too.
bolt guides are a bit more personal choice, the stock allu one can be prone to rounding and is considered weak... a choice of the masses is the hybrid tyler michaud one, which offers tool-less removal, which is a bit bonus, and also looks a bit flashier and can work as a snatch grip, but i believe the nxt has one already doesnt it?
what else have you got in/on it so far?