Does the stock PROM run a little richer than an aftermarket one? If so, why? Won't you have more power if it runs a little richer especially after extensive mods?

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

Because it is usually rich where you don't want it, and not where you do.

 

The OEM cal is slighty rich, after all plugs are cheaper then rings.

The stock cal is designed for warranty claims, EPA, and to some degree drivibility.

Once you do some serious prom tuning you'll see that most cals are garbage.