I read carefully the way you refill your cartridges, it may well work for you but its a little bit to light on safety.Refillady said:http://www.refillink.nl/PDFDocs/PGI_550.PDF
I know there is a way of filling by drilling holes in the side. But here you have to be careful because the normal cartridge is partitioned in compartments in the inkreservoir (not the spunge) where the XL version is not. See the picture
[url]http://www.nifty-stuff.com/forum/uploads/thumbs/10228_canon_551m.png[/url]