1. ditch the spare wheel and buy some tyre weld. thatll save a little. theres also alot of sound deadening in these cars. that should remove a few kgs. rear seats, are they needed ? if not in the garage they go.
2.
LHS is the forge aftermarket one. RHS is te stock one - see the bend on the metal where the pipe connects to the turbo. this is sharp corner and also squashed.
3. personal choice - even the best kits only add around 8bhp. using the diagnostic port to record the torque i got around 6bhp from fitting the air ducting, and snorkel to the standard air box along with a clean OEM filter. so might gain a little on with an aftermarket one.
4. explained this in your other thread. theres 2 maps loaded on to the ECU - IIRC the ECU can hold 4 maps. these can be switched in different manners, serial switch for the diagnostic port, button presses on the cruise control etc. to swap its switch ignition on - engine off, change map, key out wait 10-30 seconds then start the car. maps cant be changed on the fly. As said not really required on a diesel, just use your right foot more wisely.
5. see how you feel about the brakes when you get it, you may find they are good enough until the discs are getting worn.
312 mm setup will cost around £250 by the time youve bought the discs pads and the carriers, although if you know a nice scrappy you should be able to pick up the carriers for alot less than the ~£100 for the 2 from the stealers. give me a shout if your after the part numbers.
next option is the R32 golf which uses 334mm x 32mm discs a 2 pot calipers
or the 3,2 quattro A3 345mm x 30mm with a single pot caliper
Brembo brakes from the Seat Leon Cupra
or if youve got money
porsche boxer calipers with calliper carriers fit as well with the 312mm discs
apart from the straight up 312mm setup or the porsche ones ive no idea how hard the other 3 setups are to install
Hope thats some help to you give me a shout if you want more info, however im going away for a week and not taking the laptop with me