New Exedy clutch kit sound?

I have a brand new Ford Mustang boss 302. OEM clutch was sloppy so I had an exedy stage 1 organic clutch + pressure plate and aluminum flywheel put in. Also, changed bearings as we'll.

Went great for a while no noise issues.

I ran it on the highway for to 120mph, but didn't do high rpm shifts. Did around 100 mi of city driving break in. Didn't beat on it.

Now at startup, there's a sound (sounds like a metallic disc spinning) that lasts for like 20 seconds then finally quiets down. What could have gone wrong? What's this sound and where is it coming from?

I changed everything necessary, as mentioned (bearings, etc). No sound at startup. And as I've said it went well before the highway drive.

What could have been the culprit of this new sound?

Did you try to do a search on Google?

I'm fairly doubtful that anyone online will be able to diagnose this. I didn't hear a thing from here.

Anyway, from your description there's no way to tell if the noise is even related to the clutch assembly.
Does the noise change if you push or release or otherwise manipulate the clutch pedal during the noise condition? That will be the best start in the process of troubleshooting.

Second best (maybe equal to first?) would be have yourself listening under the hood (safely) during the noise condition to get an idea if it's even coming from the general area of the clutch, heck the noise may be unrelated.

The shop that did the install should warranty their work. Take the car back to them and tell them what you're experiencing. It could just be a bad pilot bearing, or it could be something out of alignment. It's impossible to know.

And John is wrong. What you did, did NOT void any part of your warranty. Installing aftermarket parts DOES NOT void a warranty. Only a failure that can be PROVEN to be caused by said installed aftermarket parts can void the warranty, and only on that failure.

Modifying a new car with aftermarket parts is not a good idea. By doing this you have voided any warranty that was in place. It would have been better to let the dealer resolve the original clutch issue and then modify the clutch when the warranty expired.