I'm going to give some advice that will seem totally off the wall but founded in historical principle. Do a TT on a fixed gear. The English were big TT riders and many rode fixed gear bikes. Do some training on fixed gear also. You can spend money on all kinds of gizmos but its all about putting out a sustained effort for a set distance. Learning to ride smooth and controlled with minimal bouncing and weaving is what its all about. Ride an 84-88" gear for a TT, and keep your RPM's up. Even go down to an 82" gear and get a good spin going so you can feel what a high cadence can do for you.
There is way to much emphasis on equipment these days. For a flat TT a good old fashion steel track bike is the way to go.