Nothing, only spare parts if you need them. Nothing really spectacular came on the 91 that didn't come on the 92. Digital dash maybe if you don't already have it. The only differences were a wider strip on the bumpers in the 91 (looks unappealing to me) and the side of the car next to the windows on the doors is black on the 91, body-color on the 92.
And relax about people writing back. This is a forum, not IM. Some of us work.