I wouldn't even think about them personally. Get a proper map. Depending on your location there is a lot of reputable dealers.
North - SGR Performance , Big Fish Tuning.
Midlands - Derby Remapping Services
South - JF Automotive
All of which will most likely get you around 140bhp. Derby Remapping is £200, they did mine and now it goes like sh*t off a shovel and its pretty much the same price as a racechip.