its near to the normal M3.

The transmission, engine, suspension and brakes only got minor upgrades.

it still delivers 420 PS (bhp) out of the V8 engine, I think they just made some changes to make it last longer during the races.

The rules only allow a sport exhaust system and a one mass flywheel, raising the power about 5% maximum


more infos here, in German though

BMW News: BMW M3 GT4: Erstmalig beim 24-Stunden-Rennen auf dem Nürburgring - Seite 1 - Auto-Sportwagen - Speed Heads

ask for particular parts of the report, I'll translate them.