Some related info from the comments:

“I’m no expert but if you want speed for downhill you want to tighten the trucks to prevent wobble right? How much is up to the rider. It’s a feel thing.”

“i think a big part about getting rid of wobbles is a lot of practice. you train the muscles in your legs ankes and feet to be more steady. i would say its 30% trucks 70% rider. practicepracticepractice!!!”

“thanks! thats so awesome!! i just ordered a rayne avenger and am going to work on ma dh. i have a dancer and i bomb that but i want some thing made for it haha. so now i got some thing to do ma jigs on and some thing to bomb the fuck outa hills!! maybe one day ill be able to come out and bomb with you guys. “fingers crossed”"