that's a very smooth curve indeed.
not bad power there, step up a housing on the turbine and you'd be knocking on 500 then, turbo is very capable of that if you up the boost. 2BAR minimum these take, 2.5 is very common and they last.
i've just gone for the junior gt3071r on my zetec turbo in my xr2 and that is very lively at 2BAR, surges a little though.