For studs you have two options, raceware and arp. Both are good. Matter of choice. 11mm or 12mm is based off your current bolt size on your head/ block. If you live in Canada you should be able to get the AAZ hg no problem, you can get them in the US but it takes a bit more effort. Myke_w here on the forum sells them. Sizes / thickness is the same as long as it's hydo. Add your location to your profile, it helps local members help you out.