Yes, it is the GT impellar. Worked out really nice. We decided to swap to 03 Cobra Dual Fuel Pumps & Fuel Tank because Walbro 255 is just plain pathetic and was not keeping up, so new dyno numbers will be next Wednesday after 03 setup installation. Fuel pressure was at 60psi, but dropped to 30psi after 5500, so we let out. However, I did make 433rwhp before the fuel pressure took a dive at 5500rpm. Power band was still climbing. So I am guessing around 475rwhp or so.