First of all, LOL at Oldman's (something extra under the hood)! I'd love to drive 400 ft/lb of torque!
My 17's are with 1/3" of stock dia. I am sure it is an MPG hit, but not much. I run 42psi rear and 40 psi front. Why? because as an old VW/Porsche driver, these things understeer way too much, and until I get a rear bar, this will have to do.
As far as lowering to improve mileage, my New Beetle is actually *raised* 2"! And it has a 30 lb steel skid plate under the engine/transaxle. My mileage did not change after these mods.
The rest is all spot on. My EGR was garotted via a VAG-COM setting. CCV mods will soon have cured the other ill. Still haven't heard a comparison between the .205 injectors and the .216 (actually .203) injectors. Smaller but has supposedly smoother flow.
Beware more than one power-type mod (injectors, chip, etc) or you will also be buying a new clutch soon. Remember, diesels do not work like gassers. Their entire power is controlled by fuel quantity, so all the mods like injectors increase the capability to deliver fuel, not the necessity of it. Keep your foot out of it, and mileage will still be fine.