Thats just my opinion, he doesn't have to listen to me.
Yes, a lot of people think it's a waste of time and money, but I'm saying that compared to what he could do, I don't think it's worth it. 1 15" or even 1 12" designed for car audio and made by a proven brand would be a better choice IMO.
Define "nasty", do you mean nasty thats horrible, or nasty thats great?