I'm planning on tuning up the car soon.With the new exhaust installed the engine temp seems to be running cooler than with the stock exhaust.Should I go with a hotter range spark plug or stay with the stock recommended plug?Also I remember heated o2 sensors being discussed with headers.Is this something I should look into also?

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1987 Firebird Formula LG4,700R4,WS6,2.73 open rear
Current Mods:SLP coated 1 5/8 in. headers, Flowmaster 3in. American Thunder cat-back,3in. Catco converter,L69 dual snorkel,K&N filter,roof console,Pioneer 1.5din cd player,BostonAccoustics 4x6plates,eclipse 6x9's

 

You needn't change plugs or o2 sensor. The sensor may be a good idea anyway if you feel like it.