The Turbo S2 is a homologation special that Porsche commissioned to comply with IMSA requirements for participating in the Bridgestone Supercar Championship series. Since the standard Porsche 964 Turbo S was not approved for sale in the US, unmodified 964 Turbos were imported and later converted to S2 specification by Porsche tuner Andial in Santa Ana, California, before being made available to the public. Andial produced only 20 road-legal 1992 964 Turbo S2 cars for Porsche North America, making them some of the rarest 964 models ever built.
These road-going “race versions” of the 964 Turbo received an upgraded K27 turbocharger, a larger intercooler, upgraded cams, as well as ported and polished heads among a few other supporting modifications. The power package installed by Andial for homologation purposes increased the power output to 322 bhp at 5750 rpm, although some sources suggest the actual figure could be significantly higher, likely in the range of 380-400 bhp.