120Gb USB HDD and USB extreme on the slim line PS2 (UK version 12), no modchip needed. However I've found games from EA won't back up using this method. I've tried using my originals of both SSX Tricky and Burnout 2.
ive chipped numeruos ps2's
to make life easier use kynar wire on most of the points except ground and live
also try and keep the + _- as short as possible.
if not confident on soldering the new dms4 is out