MR2 Turbo, strange buzzing.

running, ground, stereo, clean, frame, existing, harness, line, clipping, straight, wire, buzzing, turbo, strange, grounds, independent

Hello everyone. I bought this 93 Turbo about three weeks ago and I have been loving it. Since I bought the car I have had this really strange loud buzzing feedback sound every time I go 55mph+. It varies sometimes, being at 55mph or around 60mph and sometimes higher. It sounds like it is coming from the speakers in the front but it happens regardless of the radio being on or not. Knowing that these cars are notorious for their grounding issues I removed, cleaned and reinstalled all the