I don't know of anyone who has a 2530 that has made 250rwkw. I think a 2540 can do this. I'm sure you could achieve it with a 2530 but I'm not sure how long your turbo would last.
Moanie on this forum has a 2530 with a HKS cooler, upgraded injectors, fuel pump, SAFC, exhaust and pod and maybe a few more little things and she makes around 210-230rwkw I think.