I know for a fact the bumper won't work. And because of this I doubt just the grill will work because the bumper has slightly different dimensions. A quick trip to the Mazda dealership with a tape measure would give you a pretty clear idea though.
I'd swap my 3 bumper and hood for a speed3 bumper and hood. But they didn't do the speed in my colour (gunmetal blue) so the paintshop would be involved.