Reading Topic: aftermarket performance parts for 6S
I completely disagree with the first point. HP sells. This is the manufacturers main motivation. Have you ever heard of someone suing because their car had too much HP from the factory? No.
Emissions, yes.
Substitute the first point with cost. Granted it costs less for a manufacturer to substitute headers than aftermarket does, but the penny pinchers decide how much HP they want out of a car versus how much it will cost in each vehicle to get to that cost. For example, the original Duratec design was 3.0 and had around 250HP N/A. Designers decided they didn't want to stretch or change the Contour's front for clearance, hence decreased the bore 2.5L (not sure, someone can confim the difference between the two if they like) to save on cost. Strap emissions equipment to it and it was only pushing 170HP. The Duratec now comes 3.0 with 219HP (with OR with out the S/VT) and we all know its capable of near 250HP N/A.
Mazda could make it go to 240HP to match the Accord, but then the price of the V6 option would be driven up to the same or more than the Accord. Is everyone still going to buy it? I say YES, YES, YEEESSS! But the decision makers disagree!