ry08350z

Hey guys having a bit of an issue with my Z and hopefully I can get an idea from you guys as to what it could be.

Starting last week I've had this constant grinding noise (metal on metal) while accelerating in 1st - 3rd gear. The sound also occurs for a short time (after a drive) if I'm idling in neutral and rev up to about 2500-3000 rpm. The car accelerates fine and I have no real issues getting it into gear (shifts the same way since I've owned the car). I took it to nissan and they're saying the syncros in the transmission are bad, which I couldn't find anything doing research on my own regarding the same noise and it being related to syncros. I've had other mechanics and friends listen to the noise and they all believe it's a clutch noise.

I'm pretty lost and I'd appreciate any light you guys can shine on this issue. Thanks in advance.

2008 350z base model
54k miles
stock clutch / flywheel (afaik)
I've owned the car since 2015