[ChrstphrR]

What restrictions do you have for the class you are racing in?

Changing the shape here and there to reduce drag might not matter if you contravene one of the rules you have to abide by, for weight, dimensions, shape, functional bits that must be present, etc., etc.

I see there are what appear to be NACA ducts on the front face of the car's bonnet, in addition to the two lower ducts near the splitter. From the pictures, I can't tell if they're attached, or if the top ones are even functional.

That and, the obvious spot to me would be the front of the rear fenders, looks like a potential area to reshape so it's a smoother transition from the body -- if it's allowed by the rules you race under.

Another two big areas, which again, rule-dependant, would be potentially the short, blunt back end of the car past the rear wheels, and the underside which isn't shown.

My suggestion would be, first, dig up the rules, see what restrictions you have with modifying the bodywork -- and if any such improvements to reduce drag are out and out allowed, are not mentioned, or not explicitly forbidden, but are part of a grey area in the regulations.