I have a Cobra 29 classic thats been peek'd and tuned well. I get alot of static when the truck is upshifting and down shifting. What causes this and what can be done about it?
That or what I've done and works great is a 20 amp noise filter. Cheapest place I've seen them is Auto Zone.
Computer controlled shifting (autoshift)? You may be picking up radiated RF from the computer, relays, or associated wiring. Make sure all bonding (grounding) wires are in place between computer, transmission, frame, engine, etc., and all RF shields are in place. Make sure your radio and antenna mounts are properly bonded (grounded). RF noise is one of the hardest problems there is to locate and fix properly.
Another serious irritant that can't be cured, along with the above, is the brushless alternator used by many 2007 model engines. No matter what you do to ground radio and antenna out, noise level stays at 50% of meter. Good luck.