I have a 2530 on my car. Some people say they have same lag or less than a 25 stock turbo, but that is not true.
I love this turbo on my 20, however, is not as responsive as I would have liked (drifter).......I suppose you cant get enough response on a drifter ,...but having said that, its very good for the street imo.
Mine puts out 230kw, I haven't tried the GT-RS, but I can tell you you wont be disappointed with the 2530
If you are looking for about 220-240kw then look no further.
Cheers
Ric