Hays Street 650 clutch kits are designed handle highly modified engines up to 650 naturally aspirated horsepower (600HP for forced induction & nitrous combinations). Hays' newest 26-spline versions are designed to work in conjunction with a modern 5-speed or 6-speed transmission swap. These are true street/strip clutches for spirited high performance driving or frequent track use. The high performance dual friction disc utilized in the Street 650 has an upgraded spring hub with heavy-duty damper springs designed to handle greater shock loads versus a standard damper spring. Hays' disc features a sintered metallic friction surface and an organic friction surface. This disc does a great job at dissipating heat and fighting the slippage found in ordinary discs along with providing the smooth engagement characteristics of a street-style clutch. Hays also provide an upgraded heavy-duty pressure plate to round out this performance clutch. The Street 650 is a great choice if you visit the track often.