That doesn't add up right.My 06 charger has 350hp but at the wheel it can lose between 35-50 hp depends on the car.So loseing 40 just with those bolt ons seems high.
When the manufacturers were measuring "gross" HP there was no standard test method. The SAE net measurement defined how the test would be done. Net requires all the accessories (water pump, alternator, power steering pump, AC compressor), stock air cleaner, stock fan and stock exhaust.
Prior to SAE net they didn't have any of those on the engine and were sometimes known to use headers to get the number.
The difference between gross and net was more often much more than 40hp. Just putting an undersized crank pulley on that Charger of yours can gain you 10-15 HP at the wheels. Don't under estimate the amount of power required to turn the accessories, especially the water pump and fan.
