The best general purpose motor for 450 helis is the JGF 500TH- you can run it all day at 200W, and if you want to get silly you can put 600W through it. If you're not an electrical engineer , 200W is a good nominal power for every day flying with the Titan, and 600W is more than most batteries you'll use will ever put out- i.e., it'll fly forever with anything you're likely to do.

If you get the bare kit and put a 500TH in it you'll need an ESC- you can use the run of the mill Align or Scorpion ESCs and be very happy with them. The Phoenix 35 from Castle is more expensive, but it's more friendly to use and is as bullet-proof in the Titan as the JGF motor. It also has an excellent governor program that makes flying easier.