Hays Street 650 clutch kits are designed handle highly modified engines up to 650 naturally aspirated horsepower (600HP for forced induction & nitrous combinations). Our 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 s Clutches, High Performance, Ford, 10 Things