With the chebbies, A lot of the research & development has been done so someone can come along and bang out aluminum heads for them. They can charge less and make it up in volume. As stated above: It's just a plain and simple Numbers game. Mopar Aluminum heads are just going to be more simply because of the Supply & demand factor. On a positive Note: Mopar Performance is making more and more parts every day. They even offer Stroker Cranks for Poly Engines now. There's also something to be said for Durability. If you can get many many more 1/4 mile runs out of your Mopar engine and hopefully win more than in the end it's cheaper.