I wouldn't consider the valet mode for fuel saving reasons. It basically cuts all boost and limits the revs to 3000. You can do that with your right foot quite easily in traffic.
sounds like limp mode, and thats no fun 
that sounds absolutely perfect for when i lend my car to my relative, the car will still be driveable though wont it? do you have the limp mode/ valet mode function when you get the remap and buy the switcher?
So heres basically what I've gathered so far, but please correct me if im wrong...
I have a completely standard GTI, I go to somewhere like JKM perforamnce and get a remap to whatever bhp (i think its 240 or 250?) then i get the switch that allows me to change from standard map (200hp) or tuned map (240/250hp), no other mods nessesary and all will be fine and i will also have the function to switch to valet mode which is super slow and dull but still usuable for everyday driving.
Is this correct?
I understand that i may have to use a forge DV valve as the standard one has a weak diaphram.
many thanks people
