These have been present for a while, and I had just about given up on them, until my mechanic drove my car this week after finishing the maintenance and brake upgrade and commented on it so I feel I need to circle back and address it. I guess I have just gotten used to them, but how can I diagnose? I have Cortex Coilovers front and rear (Konis), Cortex Torque Arm, DriveShaftShop Carbon Fiber Driveshaft (with CV Joints), Fays 2 Watts Link (Center hole), TR6060 Swap, and RAM Clutch, BMR adjustable rear control arms (they are in appropriate position) Clutch: RAM Street Dual Disc Force 9.5 Clutch w/ Flywheel The vibration consistently creeps in around 80-85mph plus and doesn't really go away, getting a little worse as speeds go up on track. Having not really known anything else since we did the transmission swap / torque arm install, I just kind of assumed this was the way it was, but I guess it's worse than it should be. It doesn't prevent me from getting the car up in the 120s/130s or higher, it's just really present. The Vibration is present on street tires NT05s / Track Tires NT01s in the same place so I know it's not wheel / tire issues as it's happening on both sets. The DSS DriveShaft has CV joints so it shouldn't be as sensitive to pinion angle, and that all checks out as it should. Alignment was done by Custom Alignment and is spot on. Could it be clutch related? Should I be looking at different clutch? (I am at 610WHP right now, 522TQ) Do I need to shim the torque arm or adjust the torque arm in some way, pinion angles check out, DSS with CV joints is supposed to eliminate sensitivity to that anyways. Any input / suggestions for places I can take it to have it checked out in the bay area? Is this a job for Cortex? This is a tough one to diagnose as you can't exactly bring it up to 120+ on the street in a controlled environment. Open to any input, this is well out of my acquired knowledge so far and just looking to learn as I get it diagnosed.