Head work?

[Poodle]

Don't take this the wrong way, but you're approaching tuning this as if it's a na petrol - it's not. All these mods are generally done before serious headwork on a boosted cr diesel:

Mapping
Exhaust
Intercooler
Turbo

Also, often:
HP pump
Injectors

Not including required supporting mods, such as:
Clutch
Fuel pressure sensor
MAP sensor
Manifolds

Every one of the above will get you more bang for your buck than cams and a polished cylinder head.