My total build (from stock to basically stage 3 - IC, charge pipes, Intake, exhaust, fuel etc) cost including the tune is 10k APR you would struggle to get the hardware for 15k without labor.
There is pro's and con's to both.
Pros to the TTE480 I can tell you now. Full boost is at 3,700 - you wont get that with a GTX.
It's a direct plug and play. you don't need oil/water lines.
It uses the standard N75 wastegate control which is fully controllable and safer than a MBC.
There has been proven results overseas with their euro dyno numbers... Seem to be average of 450hp and 640+nM of torque.. which are numbers that are from a GTX2867 that APR give. But like Mark said it sits just below that of a GTX28 in total power.
I think mine was going to be the first down the track in the world with the TTE480, however it washed out... Thing is mine isn't even 100% complete yet.