it could be your CV cups getting pitted? It's a common issue and I can see the vibrations getting amplified into the chassis due to the diff collars.

 

Not cv's...the entire drivetrain except tranny has been replaced. Went all the way back to stock and the buzz is still in the shifter but not noticeable and ive had it up to 150 so i dont think i have to worry about anything braking. But as of now all upgraded parts are back on with the larger collars. I took the small ones to the front off, and the vibration through the chassis is gone and i still have the same response from the bigger rear collars.

If that makes since lol. So if you have these installed and are getting alot of vibration, try poping off the small collars.
All in all there a good modification, but i wouldnt put them on a s2000 that is driven on the street. So.me ppl dont have a problem with these at all. So my final analysis is that there is a pre existing problem with the tranny. Again i got the car bone stock with 20k and the buzz in the shifter was there when i got it.

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