Wouldn't really say you were wrong, if I didn't have the 4" speakers from a car I owned prior to the GN, I would have bought the 3.5". The install isn't exactly pretty under that grill .
because I am taking everything out in my old car and the fronts were 4", brand new Pionier's. Im really low on money for a few weeks so i dont want to let them go to waste.
Well in that case go with it. But I can't see how you going to fit a 4" in a 3.5" hole, you're going to enlarge the hole and then what the dash won't fit? Unless you squeze the 4" underneath?