First off... about the spoiler, I think it looks sleeker without it. Not really into spoiers much. I quite like how the boot has a sort of lip, how it curves up.
If it's rim colour that's the problem rather than design; Silver=Boring, Black=Cool, but bronze is better here IMO, Chrome= not quite right... I did try every good combination and found this was my fav. If it's design... suggest one, but I quite like this shape.
The sideskirt has been explained on the front view... When I do a pres... I'd definitely smooth out the SS though.

for me wo spoiler car is better than with it only backlights can be more in tuning style

It initially had reapers... but I though I'd keep the back smooth and red.

Cool miata!