Need help in picking new turbo for wrx project?

If you have the money for it, something from the Garrett GT series would be your best option for power without lag. A GT28-RS would easily get you to about 300whp and possibly have a quicker spool than even the stock turbo, due to a more efficient compressor wheel design and full ball bearing CHRA. Blouch makes a version of this called the Dominator 0.5R "Disco Potato", it's a GT2860RS design. If I wasn't getting an STi instead of a regular WRX (which I might end up with for a temporary vehicle anyways)I would probably be looking at that turbo. I'll probably end up looking at the Blouch Dom 2.0 or 2.5 XT-R "Polka Pickle"