i agree that it is very good for a "Stock" engine, but my motor is actually below stock specifications. i believe that the stock pistons for a 69 340 were around 10.5 to 1, where mine are around 9 to 1...im running factory heads, and i was running a factory cast iron intake manifold until a few years ago...but the car ran high to mid 13s with the stock manifold and the same carter carb that a 340 4bbl would have come with back then.

however, if you compare this 392 to a normal production motor, i would be willing to bet that it is almost as modified as my 340 is...i dont know what exhaust they use, but id be willing to bet that they are using some sort of high flow headers and exhaust system, as well as a bigger cam