It looks like the primaries on the Doug thorley tri-y's are 1 5/8". The only question is how do they fit on the car? I bought Hooker super comp's and both my stock steering and my rack run into the front cylinder tubes (on both sides). I do have after market motor mounts, but I don't think that they lower the motor all that much. If these tri-y's wouldn't hit the stock steering components, then they would easily clear the rack. Maybe a little better ground clearance as well? Any experience with these would be appreciated.