I am considering upgrading my Felt Z85, and ultimately I would like to replace the crank and the wheels, but can only choose to do one at this time. My question is, what would be a more noticible difference between the two? The stock crank is an FSA vera compact and the stock wheels are Mavic CXP22s. I was looking at an Ultegra compact crank and some soul aluminum clinchers. Any opinions?