the momo's are a good speaker. had them in my last boat. i put the newer MM6501's in my 03 X-2. they sound great, but need a bit more power than the momo's. they fit good in the stock clarion locations. i didn't have to cut the holes, but i did have to drill new pilot holes for the screws as they were a different offset. they can be found much cheaper than the link below, but still more than the momo's
http://www.polkaudio.com/caraudio/mm/index.php?s=mm6501 i wouldn't waste your time with the clarions, i hung them off a new amp, about 80W RMS to each crossed over at about 100-110 and i still was not happy. i ended up buying a Syn4 to power the new polks at 125W a piece and am much happier.