Better acceleration i doubt you will notice anything dude - in fact maps tend to smooth out the 'kick' you get around 5000rpm, so it may actually feel a little slower as it will be smoother if that makes sense.Best two are RS Tuning in Leeds (Well worth the drive, iv done it twice) or Tour-De-Force, both advertise in the traders section and both are top notch - dont go for something cheap, or closer due to that being more convenient - get the best you can