The pinging noise or "poping" sound is caused by a defective muffler. Somthing with a broken weld or sheild inside the muffler. It can get very loud and GM knows about it. There is a TSB on this problem from GM. My H2 also did the same thing, the dealer changed out my muffler twice before the problem was fixed. Hope this helps! BIG-C

White 03-H2-LUX

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