Tunes get boxes and remaps are good. But for best results you need one with a rolling road to give you performance figures before and after. Places with rolling roads are often able to tweak the maps to suit your needs. eg, lower torque response or faster boost etc.
I'm looking for a remap myself and a mate of mine suggested this company. They have two different types of tuning boxes. One runs at 209bhp and the other 215!!! ahhhh!!!!! not sure if an extra 6 bhp is worth £75 however, I'm intrigued to hear from people that have remapped their cars. last thing i want to do is buy a box if the clutch can't handle it
Just be careful with the diesel tuning boxes, the extra power/torque comes from an increase in fuel rail pressure and that has a limit before it will cut out. Unfortunately there's only a small amount of gain that can be squeezed from a diesel without a full remap.