If he has money to burn, why not put in a Fortin or Albins, the S4 seems like a bad choice for the weight and horsepower.
Straight from mendi's web site........
Since its' introduction the "S" series Mendeola Sequential gearboxes have been an absolute SMASH!! It's considered the standard to which all other squentials are measured. The "S" series shifting rivals any other gearbox, LMP to GT! The "S" series with its' 19mm wide reverse gear and removable face plates makes maintenance a no brainer. The full contact shift drum and billet shift forks are designed to be off-road rated. The S-4 platform is equiped with 1.090" wide driving members. The S-5 driving members have .800" wide faces. This fact dictates that the S-5 torque rating be derated by 20-25%. The 8-lug dog rings are utilized in heavy torque loads 450-650 lbs ft. applications (to 7500 RPM). The 6-lug componentry handles medium torrque loads 250-400 lbs ft. and high RPM (to 9500.) The optional 935-300M drive stubs handle any application.
Currently the S4 and S5 are the most used transaxles in big horsepower sand buggies, outnumbering ALL other transaxles, combined.
From Glamis to Baja, they are the Royal Family of Gearboxes!
S4 | S5 Transaxle Options:
· MD series diff (10 or 12 race cars)
· Reverse rotation 4.86, 5.14, and 5.42 ring and pinion
Applications Max Tire Size Max Engine Max Vehicle Weight
·Sand Buggy 1450 Desert Trak ·LS1, LS2, LS6
2,800 lbs
·Medium Duty Pre-runner 1650 Padla Trak ·SUBARU TURBO 3.0 6 CYL.
·SCORE Class 5 32"or 35" BFG BAJA T.A. (shaved) ·NORTHSTAR Max HP
·SCORE Class 10 425 - RACE CAR
·V4 or V6 Class 1 500 - PRE-RUNNER
600 - SAND CAR