Well, sorry...in your post, you asked for "tweaks...like the registry hack." There's just a lot of repeated questions in regards to this title, and further, about registry tweaks in general. The search function is so rarely used...
Get Rage 3d tweak. It has an inconsequential footprint in Ram, integrates into your advanced properties in the display tab, and comes with instructions for just about every tweak setting possible in the registry, separated into an OpenGL and DirectX sections. It also has simple overclocking controls, per-game settings, and custom resolutions are a no-brainer. The only thing it lacks is a custom skinning utility.