I had my 7.5 gti mapped using Mountune hand set. I can tell you with all honesty, it totally transformed the car. The delivery of power and torque is unbelievable. I ran the map along with their induction kit. Which i recommend, to get everything out of the install.
I did have some issues with the handset to begin with, this was due to them supplying an R handset, not GTI. But they were really helpful in dealing with the issue. I could have had it swapped , but decided to let them send me down the correct file and installed it onto the handset then onto the car. From then on it was faultless.
My car was the GTI pp. It upped the BHP from 245, to around 310 ish. Massive gain in my eyes. I sold the car back last yr, May time i think, and bought a mk8 clubsport. I reckon the GTI was as quick, if not a little quicker.
A note of caution, i did the remap almost 3 yrs ago. Since then i know that they have now dropped the 57 brand which was their vw part of the mountune brand and they just have it all under one name now.
Not had any dealings lately with them, so do your homework and research before buying.
Hope this helps a little. If Mountune were to release a map for the mk8 clubsport, dont know if they have, because of how impressive the map was on my 7.5 i would definitely sound them out.
