Are you looking for a springer or a PCP?
The RWS 350 and 460 will give you an honest 800 fps with a 17 grain Predator pellet. That is pretty good. Don't believe their claim of 1000 fps. I have chronoed quite a few of both models. They are plenty powerful to drop squirrels instantly with well placed vital shots.
I think there are some PCP guns out there that boast some pretty impressive velocities. Unfortunately I have no personal expirience with them to draw from.
The Gamo rifles talk about some smoking fast velocity too. Beware that they are not rating their guns using lead pellets. Take all published speeds with a huge grain of salt. You will never reach those speeds without aftermarket tuning and tweaking.
Hope this helps.