If you want to do it go ahead but use radiator paint. It doesn't build up like engine paint.
If you have to put something on there the ralliart would be better imo. It would be less ricey to lye and put mishimoto, ETS, or greddy or something. Thats just posing then.

might as well paint "GOING FAST" on it.....

I painted mine gloss black and painted Ralliart in red.
looks good with the front guard off, but barely noticable with the car complete.

The black FMIC does give it that stealth look though.