First things first, forged internals and big TBs can wait.
Some adjustable cam pulleys would be easy to push thru developement, and would probably be hot sellers. The exhaust should have to have timing pickup adjustment too.
A SS header would also be easy and very marketable. Since nobody else is moving on one yet.
Light weight 2 and 4 piston calipers would be nice. 4 piston opposed in front, 2 floating in back.