Hello
After all this time my little A2 work not bad. It has 137.000 miles now. It run on E85 without engine light. I know this fuel isn't available in UK but in France it is cheaper and can improve the engine power. Just it need 40% more injectors size and an adaptation for cranking in cold temperature.
Here a sum up of all the work done with parts number if someone want to optimize the 1.4 BBY
Intake manifold Polo GTI 036129711BJ
Gasket ELRING 049.141
Injectors Renault Megane BOSCH 0280158170
Denso to EV1 adapters on Aliexpress
Fuel Pump Audi TT Magneti Marelli 313011300015
Fuel filter with pressure regulator Bosch F 026 403 006
Throttle body Golf 4 036 133 062 M
Gasket AJUSA 01121500
Aliexpress silicone hose 63mm length 76mm
The EGR has been remove and a plate is now on the cylinder head.
AND A BIG WORK on the ECU, because with the optimized intake the ECU detect a manifold leak due to manifold pressure change. The DTC P0106 make me nightmares
I work from a Golf 4 software and i adapt it on the A2.
I don't want to modify more with for example a direct intake kit. It will be noisy and it is enough for now. When i will have time i'll go on power test bench to have the numbers of all this work.
About the interior i just put Audi TT heather leather front seats. It is clearly better in therm of comfort.
I bought an Audi A3 8L wiring on eBay, and a climate control panel Audi A3 8L0820043J. I just need to keep the electronic from A2 and cut the panel with the good size. (A2 climate control with heater seat is so hard to found)
Thank you A2OC for all the resources, i very often search informations !