My 57 T Bird with a Mummert head 312 with around 425 horsepower insists on making a right turn on a hard launch from a dead stop. Toploader 4 speed, 3.89 traction loc rear end, rebuilt set of original Traction Masters, Diamond back radials, station wagon rear springs. The first time it happened I ended up setting sideways in the road headed straight towards the ditch on the right side of the road. Scared the crap out of me. It’s never done anything like that before. Easy enough to light up the tires but it always went in a straight line before. Not that it should make a difference but it didn’t happen until I replaced the antique Headman headers with FPA headers and switched the stock mufflers and tailpipes with Turbo mufflers and 2 1/2” tailpipes. Picked up horsepower and torque with the change. I’m thinking a problem with the Traction Loc or the rear suspension?  It starts to go straight and then the back end comes around and it starts to spin out and head for the ditch. Goes straight down the road otherwise. What’s the problem?