I wouldn't have thought downforce in the front would be a big issue. At speed, usually it's the back end that tends to lift on most cars.
The little roof vortex generators
can help a bit with rear downforce by delaying the flow separation. Might slightly improve mileage, too.
If you need/want more downforce overall for traction and racing, well, that's a whole 'nother ball o' wax.