Your best bet will be Thorney Motorsport. They are good enough to have the backing from vauxhall, and are the only modification company that can do there remapping etc on your vehicle without it losing its warranty.

Also, if our car is out of its warranty, they check the engine over before a remap, and if they're happy its in good condition, they actually give you a 3 year warranty on it!

I work for a vauxhall dealership and that's who we have to recommend.

Matt