GTM Stage 1.5 Pulley Recommendations
 

I'm about to switch my car over to e85 and dyno tune the car for 550hp but I know I'll need to pull more boost to do so. I'm currently running a 94mm pulley that came with the 1.5 kit but I was thinking about going to an 85mm pulley to achieve 12 psi of boost. I used an impeller rpm calculator and found that with the stock crank pulley and the 85mm SC pulley, the impeller rpm would only be 37,359 which isn't near the limit for the Rotex C38-61. But I have read around here and seen that other users say you can't run that small of a pulley on the SC because it will max it out. Any suggestions or advice is welcome!

I have the 1.5 kit. Tried the 90, 88 & 85 mm pulley's. I got best results from the 88mm pulley. the 85 mm pulley seemed to lose top end power. I was remote tuning at the time of the changes , but the power was better overall/top end with the 88mm .
Final dyno tune by Dynosty- 479/360 to the wheels with the 88mm.

Do you have any fuel system modifications done? I'm also looking at doing a return line fuel system along with 1000cc injectors and a DW400 fuel pump upgrade.

I used the Fast Intentions Fast 500 fuel return kit, ID1100 injectors and the fuel pump (walbro 255 )that came with the gtm stage 1 kit.
( I upgraded to the stage 1.5 kit and kept the stage 1 fuel pump. )

I ran the 85mm pulley and was running 12.5 lbs with 522hp/400 tq ....never lost any top end power was strong all the way up ...but to be fair I was running the stage 2 supercharger..ran that pulley for 2 1/2 years....also the 85mm put your supercharger at about 91krpm at 7k motor rpm and 96k at 7.5k motor rpm