Bone Stock 318 Magnum dyno run.

That's cool - are you trying to break into the PCM coding or just looking to document changes to physical parts?
I think it is down a bit more when you consider it's not running any accessories or the water pump. Probably closer to 30hp less if it was run with a true "net" testing type accessory load, maybe another 5-10hp gained by runing the headers and not full eexhaust which is what the factory ratings include. IMO anything 15 years old and running acceptibly at 300K is worth celebrating when you consider the design intent was to last the payment period.