None of the product mentioned will even come close. If your porcelain tile is grade 3,4 or 5 you will need this
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260690071601&ssPageName=STRK:MESE:IT
Follow the instructions on this page and you will be fine.
www.toolvolt.co.uk
Joe
November 2010