Hi,
When I rev the car and keep it at 2000rpm, I hear this noise coming from underneath the car(middle section). I was suspecting a heat shield at first but doesn’t seem to be that. My other idea might be something in the tranny. But a new disk clutch and bearing have been installed. This change could have losen something in the tranny ? Or it can be the exhaust line that does this sound. Any ideas other than that ? I am waiting for the weekend to lift the car up and go see underneath.
What does it sound like?
Sounds like 2 piece of metal. A little rattle.
It sounds like from what you’re saying that it really boils down to whether or not the sound started right after the clutch work. If yes, take a quick peek at the exhaust/shields/hangers to double-check everything but then straight back to the shop…
Otherwise i’d take a closer look at the exhaust system, esp. since the rattling is at a certain RPM.
But who knows right. 
Good luck.
Your best bet would be to find someone who would hit the gas while you were laying down so you can pinpoint where exactly where it is… and start from there
Clutch or not, on the neutral, at 2000rpm sound is there. let’s open it’s not in the tranny… :x
Not sure but it seems that it is the mainshaft ball bearing. Can it be that ?