Had the same pinging noise with mine, took it to Holden and they said it was something to do with the AFM, anyway just changed the manifolds over from the original cast to the stock HSV headers and the pinging has gone completely.
DESCRIPTION: Wanted to Buy
ITEM: VF SSV Redline 19inch black wheels and tyres
LOCATION: Endeavour Hills Victoria
CONDITION: Used
DELIVERY/PICK UP INFORMATION: Pick up Melbourne metro.
PAYMENT OPTIONS: Cash on pick up
CONTACT DETAILS: Please pm
OTHER INFO: No gutter rash...