Ok guys I just had my clutch replaced under warranty from Isuzu Ayala Cebu.
So for those of you who have been experiencing that horrific sounding clatter sound when you depress the clutch when idling/parked here is what we found during the service -
defective clutch spring.
It wasn't the release bearing as we earlier suspected - that bearing was perfectly intact. They simply replaced the clutch disc with an OEM type. Wish I could provide pictures but I didn't bring my cam at the time of service which was done in less than two hours. As it turned out, in 2008, they have replaced defective clutch springs in about 5 D-max units.
Kudos to Nolan and his super efficient 'Pit Crew' who made the replacement look like child-play. They even checked my suspension, some electricals, fluids, etc.
Mystery solved
.