I would go for the hks gtrs if you had about 2.5k to spend. Best response, everything will bolt up perfectly, because it's a full kit. everything is included, including a heavy duty actuator, bolts, washers, lines EVERYTHING.
If not, i'd go for the gcg highflow - cheap, striaght bolt on, ball bearing. It'll make 250 rwkw EASILY. responsive.
PS: if you're looking to get a highflow, and wanna borrow an rb25 housing to take to gcg so that your car isn't off the road for as long, i've got a couple here. I've been lending them around to forum guys to help people out.