I introduce new products for Mopar engines all the time. Sales are fairly low though so it is hardly worth the effort. I design new parts more as a hobby than as an actual business. If I didn't have other sources of income I'd most likely starve to death making Mopar parts.

There aren't very many guys who make a living selling Mopar parts that they designed themselves. Indy is about it, maybe KB, might be a few others out there. There are some folks who make money reselling parts into the Mopar space. Hughes, Mancini, Mazzolini, etc., but not very many guys who can actually fund their own R&D and manufacturing. There just isn't enough money to go around.