Power adders and Forced induction....2 different things IE Nitrous is a power adder, but its not forced induction, in fact it does quite the Opposite, it creates more vaccum presure.

I concider anything that aids in the motors duty of making the most power a power adder. Now if its a replacement part of the actual internal combustion process(IE heads, cam, pistons, rods Intake man, etc etc etc) then I concider that a Modification, not a power adder, But having intake, exhaust and DR's on a mustang is not modded, its STOCK!