With regards to intake and re-map, I would recommend a panel filter in your air box, get a GFB DV+ upgrade for your turbo and a down pipe and sports cat fitted, this should net you anywhere between 30-40% power increase without being obvious to the untrained eye.
Lowering, well, coilovers really, but also consider bigger brakes up front if you're upping your power. Golf R32 (a.k.a. 345x30mm) front brakes can be bought for as little as £300 but you will appreciate every penny.