I guess you could hit 320 on a T28, but that would be on a dyno with cool water running through the I/C (i.e. the source of the extra 25hp), but why bother? If you want that much hp step up to the T3/T4 kit and doing it without pumping hot-as-hell air thourgh the intercooler, that way you could achieve the same power, and more, with less thermal stress on the combustion chamber and internal due to a lower intake temp.