i've had a GCG R33 highflow (with standard rear housing) and it was a cracker of a turbo for the budget conscious. I now have a GT-RS turbo.
THE GCG was a great turbo, sensational bang for buck for about $1K second hand. Compared to the GT-RS i found the GCG gave a bigger "whack in the seat" factor when it hit full boost, the GT-RS is much more responsive and smooth in its delivery. Its been a long time since i've driven a stock turbo car, but the GT-RS spools so smoothly and quickly, its hard to fault it. THe GT-RS is much smoother and I found it very street friendly. I live in suburbia with mostly 50km/hr zones, so i need a responsive turbo.
It also comes down to your tune, the boost you're running, etc etc.
My GT-RS is currently making 242rwkw, my tuner said there is plenty more in it, but i am more than happy with the current tune, nice and conservative, yet plenty of power.
Short story, i love my GT-RS turbo, they do cost a fair bit, but once you've got it up and running you'll be more than happy with your investment.