Could be injectors
Could be the noise of the timing chain rolling over under the valve cover (most likely)
Could be a bad pully/tensioner
Could just be the exhaust heating up - expanding.
1999 Silver Frost SVT
#609 of 2760
Quaife, lightened SVT Flywheel, SPEC stage II clutch, removed resonator, k&n drop in - various other goodies too.
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