Try a search for "remap" mate. Plenty of threads on this.
R-Tech usually come up as favourite as they are cheaper and will get the most out of your setup, with customer service you can't fault, you get a health check before and the car setup on the Dyno, whole process takes 2-3hrs.
Revo will get you similar figures, but as it's a franchised service it's just a guy plugging a laptop into your car and uploading a map. A decent installer will do some logging and adjusting of the settings to make sure the car is happy with what is being asked of it.
With Revo it really is down to the guy that uploads the map, so if you do go Revo make sure they know what they are doing