there is another company just started offereing similar parts, and people are watching the interior parts on that i would think. plus there are several others doing similar products.
if it was me i would try and find the niche, something no one else is doing. and the things you mentioned that jumped out were parts no one else offers as yet. like the washer jet covers, the plenum.
i think the plenum might have the biggest returns, there are a few people who like the kinetix plenum but don't trust it from cracking. as apparently the new revised ones still do. if you could offer a plenum that increased the air to the front 2 cylinders like the kinetix does, but made form CF which shouldn't crack you could be onto a winner. not just here vut on the yank forums as well.
i love the polished plenum but i can't be arsed to polish my own or keep it maintained as well.