W2 heads Vs W5 besides weight is a big increase in performance?

They can be made to flow better. They are made of aluminum, which dissipates heat better, but that can actually decrease performance if the compression is left the same. They are much less expensive to repair if damaged.

Those are the main advantages I can think of this early in the morning. Check out the flow numbers at Shady Dell's website and see what can be done.

Plenty of guys have gone really fast with W2s.