The SC12 from the Toyota Levin/Trueno can be uprated by adding larger pulley's on the crank end of the drive belt (the s/c end pulley has already been reduced in size since the AE101 or '91 onwards Toyota's). As far as I know the teflon seals in the s/c are rated to about 10,000 rpm which would equate to a maximum of 14 psi in the 7000-7500 rpm redline Trueno/Levin). There are several companies doing the uprated pulleys including HKS, Blitz and Cusco. The HKS will take you from 7-8 psi through to around 10-11 psi I think. The Blitz is the biggest one for reliable horsepower without modifying the computer settings etc in the Toyota's. The Cusco is the biggest you can fit overall before the pulley starts interfering with the other parts near it. However when fitted into the Toyota's it definitely requires a bigger intercooler modified mapping and it apparently does not idle very well at all.
Of course most of this info relates directly to the installation in another kind of car.