Traction control is legal....kinda.
Thanks for the page @Johali
Let me give you a short class on what is, and is not, legal.
What IS NOT
Using wheel speed to actively manipulate ANYTHING on the vehicle.
Knowing you're on a ****** track like we were this weekend in oklahoma city, and having plan A, plan B, and plan C for getting down the slip and slide.
Essentially, you know approximately where the tire is going to spin, based on looking at the track as well as the on board data recorder. Accordingly, you know where to yank a bunch of power out.
Our "normal" timing control curve ramps from 29 degrees at 0.01 seconds to 25 degrees at 0.40, stays at 25 degrees until 0.80 seconds, then ramps back to 29 degrees around 1 second. This while running a 47:52 pulley ratio for about 27 pounds of boost.
This weekend after smoking the tires twice in the same run, we went to a 48:52 pulley ratio for about 25 pounds of boost, reduced main timing to 27 degrees, and changed the timing curve to ramp from 27 degrees at 0.05 to 21 degrees at 0.25, stay at 21 degrees until 1.10 seconds, then ramp back to 27 degrees at 1.80 seconds.
We were still slipping the tire pretty hard, but not enough to cause detrimental issues.
The other option, which I will be using on my truck, is to use an air throttle system. This uses a pressurized cylinder between the throttle cable and induction system, allowing the pedal to stay wide open, but the actual throttle to not be wide open. Valves control how quickly the air leaves and re-enters the solenoid, which allows the throttle to apply progressively based on a defined time. Some people have the throttle ramp as slow as 3/4 second.