Mugen and Honda ran a single make racing series using the City Turbos. The cars were based on the production vehicles as were the motors. The motors had larger exhaust, injectors, production type turbo (with 22psi), production type intercooler, and a modified camshaft. These cars did the standing 1/4 mile in 13.5 seconds (which isn’t bad for a frontwheel drive car set up for circuit racing).
They ran very fat tires (9” front and 7” rear). The official Mugen figure for power output is 138+hp @ 5500rpm but the torque is around 22kgm @ 3500rpm (standard twin cam VTEC 1600 has 16kgm, NSX V6 has about 28kgm). It takes little work to produce these power figure in a street motor. The cars from the one make racing series were bought by an Australian entrepreneur with the vision for continuing the series in Australia. Unfortunately all the vehicles were in a warehouse in Osaka waiting to be shipped when an earthquake struck and buried the lot.
If you were racing your Mugen City Turbo II in the mid 80's, chances are are you had this Mugen competition oil cooler kit.