Are there any major differences in performance between a 1988 and a 1989 Suzuki Samurai?

nope, both 4 cyl piece of slow crap.

Nope both roll over just as easily they are not called TIPMOBILES for nothing

''The 1988.5 model Samurai was retuned for better on-road use in the United States. This revision included softer suspension settings and a larger anti-sway bar to reduce body roll. A lower 5th gear (.865:1 vs the earlier .795:1) increased engine rpm and power on the highway, and improved dashboard and seats made the Samurai more comfortable.''

The big difference was the introduction of fuel injection.