My turbo appears to be a 2510, makes 200rwkw no probs. Its struggling to make more, but the mid range punch at 1.3bar makes it quite fun to drive
I would sacrifice a bit of lag though for more top end any day though......
It does drop off after 6100prm, but this is more cam related I think, as the turbo is still making full boost.
Never been in a 2530 equipped RB20, if I where you I'd get the new 2530KAI, that would be perfect, or if you don't mind lag, a 2835ProS with a .63 exhaust housing
Mine has made 200rwkw at .9bar, and makes 208rwkw at 1.3bar, but I want to have a go at tuning it at 1.15bar and adding more timing, as I think it would make more power up top due to less boost/pressure in the exhaust housing
They are a good turbo though, I would probably rather a 2535, but seems most people are only making a few kW's more than my 2510, so its a bit of a hard call
my 2510 make full boost at just over 3600rpm in 4th gear