Is this a physical restriction or something that can change via programming? It will not allow me to go more than 85mph, how can i change this?

???

Ok, I'll bite. I've had the engines apart & the trannys apart. I know of no restrictions and I've seen nothing in the manuals that mention it. Certainly not a mechanical thing. That said, I've never had any of my vans that fast, and I wouldn't advise it. Its a Van!!
It could be that there is an ecm program restriction, but I never stumbled over it in all my thumbing through the gm books.

ok its a van...so what are you sayin? Theres 110 on the dash and its a V6, dont be fooled by its appearence.