As RUSSGT said, look up Tino's build, ou won't find a better example of how a ej should be built.
As for 450hp atw, it's been done by a few people way before i could apply for my learners back in 03.

Look at the time of sale..and it was built way earlier. 600hp atw

http://www.perth-wrx.com/vb/sale/873...ac-terror.html