On a few instances I've gotten the Jimmy well beyond 80, but in terms of comfort and stability... well, it depends on several conditions. If there is no wind, the downforce from cruising at 80+ actually seems to make the truck feel more planted to the road and the steering some how feels tighter. But, add any bit of wind to the equation, and it starts to feel pretty unsafe. I've taken it on 300 - 400 mile road trips averaging between 65 and 75 MPH and it's acceptable. With the new Bilstein 5125 shocks, it drives a helluva lot less harsh than it did with the quad shock setup, and it also doesn't hurt that i had my seats re-foamed and bolstered when the interior was redone.