I've got the .810 MP Drag Race bars in my 62 Valiant Drag Week car. Right away I had the adjusters near the top to achieve the ride height I wanted, and after four Drag Weeks and around 5500 street miles they are completely shot and will no longer hold up the front of the car. This is in a 3000 lb car, small block with aluminum heads and aluminum radiator. With my experience the .860s are the smallest I would go. I'm going to put .890s in mine, as I think I don't need the front end that loose at the power level I'm at.