a cop does have probable casue to pull ya over, if a cop wants to he will. and then if u have any sort of aftermarket looking car (even if ur civic has a oem tach, rims, chrome exhuast tip, non oem deck, all to mufflers and stand out colors and lowering system)
a front liscence plate is really just an excuse to pull ya over for more, so it is probble casue
now, if u have a fropnt liscense plate and they pull ya over, u can sue that cop for harassment. its just safer with a front liscense plate. plus i think a front to the side but not over the side vents is a decent look.