Another COR thread

[MisterJerk]

I have recently noticed that my COR (or something in its general location) is making a single click when I rev the engine past 1500 - 2000 rpms.

Is this normal? My car seems to be running fine. She doesn't seem as fast as she was, but that might just be my perception.
might be related, might not: Super hard to start first thing in the morning.

A little bit of history on what i got:

Blacktop 20v block, crank, rods, and pistons. 16v oil pump. No oil cooler. Toda 3.7kg flywheel
Big port(zenki,TVIS, w/e) head, 0.5mm shave, light port and polish. TRD 0.8mm head gasket.
No A/C, no PS. No EGR valve. 20v FPR, not attached to vacuum. Charcoal canister connected. No fuel buffer thing, just straight banjo bolt. No electric idle up.
Ignition timing set to 0* , BCPR6ES NGK plugs.
I have been running this setup for about 2 years now.