Time to upgrade. I have stock componets on trek 4300(Suntour crankset,sis shimano front der and acero rear der.) I want to do more touring with this bike. I was thinking along the lines of xt crankset, xt rear der, lx cassette and chain. I def have to get new chain and cassette. They are slipping. Should I spend the money on front der and crank or would I be fine with whats on it already?