Well, I recently got my car tuned (numbers in sig) so of course I'm going to test it out. So I try to be alittle easy on my car, start in 1st gear roll, hit the n2o at arond 3500 RPMS. Spun like crazy, shift light came on and I backed out of it and instantly noticed a NEW sound.

The sound is coming from the tranny, only on deceleration. It's a "sshhhh" or whining noise. Sounds like I have a supercharger on my car. I can hear it the most in 1st gear, the higher I ride the RPMs down, the louder it is. If I put it in neutral the noise stops. It also seems to quiet down after driving it some.

I'm guessing a syncro(s) got messed up. Tranny still shifts fine, guess it couldn't handle the TQ. Sucks ***, because it was the only time I tested the n2o out.

So anyone have an idea?

 

If you didn't shift under spin/ load, the synchro is not damaged. I suspect you are hearing the coast load side of 1st gear or you diff gears.Impacts are what breaks the gears, I don't think you did that (yet).

 

It spun alright, but as soon as I saw the shiftlight come on I hit the clutch and backed completly off the gas. The noise sounds like it is coming from the tranny, and not the rear of the car.