All used on same engine setup TRACK CAR 4agte
brand new kkr280 made 170kw on 16psi failed after 3 track days, bin job, worked well till then
t28bb (jap s15) made 169.5kw on 18psi brilliant never failed still got it
STREET CAR 4agte
t28 non bb made 129kw on 12psi spooled up hard as fk but dropped oil rear seal, bought it 2nd hand.
t28bb made 135kw on 13psi didnt seem to spool up as hard as the non bb item but is alot more reliable!!!!
would reccommone t28 non bb cheap and good turbo