:use a turbine housing with an A/R of .86. This higher A/R number allows better flow of gases at high engine RPM. The reason I noted that was because there was a dynochart from a car which made just shy of 600RWHP also and claimed it was with HKS2530's, but it was noted that they had an A/R of .86, which would make it a disco potato turbo.
There is more to the disco potato than just the turbine housing A/R being different. Like we have agreed upon before, the compressor wheels are different