i had a completely bone stock gsr in a ek hb, stock inj, stock cast iron header, stock clutch & flywheel, stock p72 ecu, no butteryfly valves, off the self intake, 2 1/2 inch exhaust, ran 14.4 at import showdown.

simple bolt ons, IHE, a good lil tune, good tires and a good driver should do high mid 13s with no problem.