The WORK S4E 91mm compressor wheel was designed from the ground up to provide great power delivery without overwhelming the 96mm turbine wheel we all know and love! Customers have reported spool times equal or better than the S480 with almost another 150 HP on tap at the same boost level. We were focused on providing the best turbocharger possible for the LS/LT market, and I think we hit a home run! Designed to perform very well in the 22-28 PSI range, this unit is perfect for the SBE LS customer that is wanting 1200 flywheel HP without having to push a crazy amount of boost. Power delivery is super smooth and these guys work great as twins on a big-block application. 2018 Drag Week class winner Frank Saponaro made an impressive 38 psi of boost with only 37 psi of backpressure on his record setting pass. Reliable and affordable, the S4E-91 is a top contender in the mid-frame category. Contact us today with any questions regarding our unit, we will be more than happy to help!