Cams can make you go backwards not set up properly (not saying yours are but your set up definately sounds lacking in the response area if you are considering a smaller turbo).....KW aint the be all and end all IMO Torque is, and I know from my own experience i went from 6200 Tractive effort on the dyno to 6800 just with 2 psi with a 3037 and would not look back, absolutely awsome turbo for a 25. Take what you will from what i have achieved but just remember this is the biggest turbo HKS does for a 25 and they are known for performance and response.....So for a reliable 250 very very easily i would recommend a HKS3037 and then if you get bored(and you will everyone does chuck a couple more psi into it and knock on 300's door) Try doing that with a GTRS or similar. I can't stress enough that a decent tune plays a huge role in your outcome.