not necessary....depending if you have a rocking frame. I admit that buying a TT bike is much cheaper, but you don't get the benefit of actually building it yourself. I have a Trek 2300 Pro from 1991 and i put on a Syntace/Prof Dgn aero. Reroute the cables. I am in the process of getting Prof Dgn Fast Forward and Fi:zi'k Arione to bring me closer to the front. I also have a Cervelo P2K, they ride about the same.

M8, you also gotta remember, you are in Sydney, I am in London, Ontario, Cervelo HQ is two hours away. Shipping and all that good stuff.

Cheers