Doesn't the manual say. I would image the stock plugs would be good for 75-80k miles. But mine lasted 9k miles. I put in copper plugs one temp colder. Platnimun sucks. Mine were gapped .054 in my Cobra, but chech under the hood. It will have the GT gap.
2001 Performance Red Cobra Coupe
285rwhp 290rwtq Stock
OIL PUMP GEARS BROKE Oct 2003
Houston Performance forged 9.1:1 short block
PnP heads with FR500 camshaft kit
HPP ported intake