I get a odd noise on the drivers side (maybe on passenger but I don't hear that side while driving). It's kinda a TWANG noise. Happens only on compression in Bigger Woopy Do's, Like today on the way home went through a dip in the road at speed and TWANG. I have Bilstein with Toytec HD fronts. They are on the bottom setting (no lift from the adjustable perch). To me it sounds like the spring is rotating the bottom perch a little making the noise? I have 85K on the stock suspension. Stock everything except the Struts/shocs and Springs front and rear. No rear bags. I just had a thought. Literally right now. I do get a slight rub mark on my Upper Control arms. I usually don't see the mark but it happens every once in a while. This noise is not often. Around town once a week or so. On the trail a couple times a day. I wonder if I am hearing the raised lettering of the tire hitting the Upper Control arm. Or the spring perch moving a little? Any other ideas?