What do the STi hardened strut mounts do to the suspension ? Are they hard to install ?

I'm just starting to really get into my Subaru but am really clueless about mod installations. I did a search on strut mounts but didn't understand anything.

 

Do a search for group N mounts and you'll find a fairly good explanation. Or go to www.nasioc.com and look for some posts by BigskyWRX, he deals a lot with suspension questions. Or head-over to Paul Hansen at APEXJapan.com or Dave at Rallispec. Either of them can answer all your suspension questions. Don't worry, I'm doing the same thing myself, and it's no fun sorting through tons of semi-useless information.