Maps maps maps

Hi all, well I've now started with sorting out navigation using a spare Ipad. so far I've used Sygic maps with a bluetooth GPS and it works great for general street driving and also some more obscure tracks (Lennards in the SW of W.A. comes up a treat). But i'm looking for something a little more in depth and accurate. Now I've read that people are installing memory map and then getting an .ipa file of maps and chucking it into the apps map database .. well I just tried and it doesnt seem to do anything .. anybody know what and how I can proceed?