its a HKS legal
they are not designed to really push more than street application
so you need to change for a good flow on 600/550
change the turbine outlets, down pipe to something better (HKS is ok, but much better options out there)
all the best in your search
il be going for similar power, so i went Midori turbo outlets, tomei turbos, midori Ti down pipe, midori Ti Muffler
hope that helps.