I bought an 08 G37 Coupe S 6 months ago with a Z1 clutch kit and lightweight flywheel. Once I got the car home I noticed a noise from the throwout bearing. My local shop told me I needed to replace the bearing so I scheduled that job with them. Once they got in there they said the clutch was staying partially engaged while shifting and it was 90% worn. The aluminum flywheel was also blue from overheating. I then replaced the clutch and flywheel (the model they used was a Power Torque Kit pn K52472-1sk. Once I got the car back I had a noise while shifting and a rattle while in neutral. This rattle goes away when you step on the clutch or put some pressure on the shifter. After bringing it back in numerous times they told me the noise was coming from the input shaft bearing on the transmission. They sent me to a transmission shop who replaced my transmission for 3k only to find that the noise is still there when I got my car back. Now I am 5500 in the hole on these repairs and am still having problems.
My suspicion is that the flywheel is not right for the car causing these vibrations and rattles while in neutral but I cannot find any specs to backup that theory. Has anyone had similar issues or have any idea where I should look for the problem?
I appreciate any help with this as I am feeling very hopeless on getting to the bottom of it.

 

My car rattles (6MT) and I absolutely hate it, but according to forum posts, it's normal for these cars.

 

Adding in my car making a bit of a rattle while clutch is out and car is in neutral. I was concerned something might have been going wrong but it's just a little bit of noise that most people probably don't notice. Only other thing I can think of would be normal chatter from aftermarket flywheels.

 

I've heard aftermarket flywheels rattle, but my stock dual mass flywheel does not (and I'm on my second one).