Actually, the '13's are rated at 420 HP. Did you dyno the car in 5th gear? We need your SAE numbers.
Yup, gain 8HP, lose oil squirters on the pistons.
2011 GT Premium Brembo ("Spirit"), Kona/red, 1.5" drop, Goodridge SS brake lines, 3.73's, LPW Ultra diff cover, HID, JLT oil catch can, FRPP ProCal II w. Airaid, FRPP X-pipe, Roush axlebacks, Boss LS tranny cooler, Boss oil cooler, Boss radiator, Torsen T2-R; FRPP "K" springs, struts, shocks, mounts, anti-rollbars, upper strut brace, poly bushings; Barton shifter/MkII bracket, CG-Lock, Grabber knob, silver Forgestar CF5 19x9 35mm offset, AE aluminum driveshaft