For customers who bought our RR670 supercharger kit for Lexus RCF and GSF, we are glad to offer an upgrade to Stage 1 kit. This kit includes a 90 mm pulley, ethanol kit, and upgraded Stage 1 tune. The increased power is significant, as you can see from the dyno chart, we are getting 638whp which is about 750hp at the crank! Please note that e30 blend (30% ethanol or about 25% e85) is required for Stage 1.