R-tech is the way to go, even at that distance.
Fit the Rev G Diverter valve before your map.
HAd mine done at R-tech, went in with just an intake and ran 193bhp and 222ftlb.... left with issues but ran 232bhp and 286ftlbs nik said it was poor and said he thought the turbo was cracked... it turns out my turbo was cracked
Statllers in sheffield fitted me a new borg warner K03 and all was UNBELIEVABLE. Went to the Charity rolling road day and my car ran 267bhp and 324ftlbs... at stage one!! no other modifications, no fuel additives.
R-tech are in a different league!