Firstly, the PD150 is nototious for over delivering powerwise.
Speak with anyone that rolling roads these, and they will tell you that most PD150's make mid/high 160's as standard. Many are in the 170's. Mine was rolling roaded at 186bhp at our rolling road day at AMD last year. Mine was a totally standard car, never fettled/fiddled with, just well looked after and fastdiously maintained at local stealership.
In terms of what you can do tuning wise, it follows a path similar to that of the 1.8t. Re-map and exhaust will give you around 200bhp. Beyond that, you're looking at turbo upgrades etc, which is where the cost/power gain ratio beomes very steep!
In terms of cost, AMD will charge you (approx):
£500 for remap only (should give 195bhp)
£1000 for remap and miltek exhaust (should nudge you over 200bhp)
£2250 for remap, exhaust and hybrid blower (power ITRO 240bhp)
Bare in mind that the torque these engines produce will be far in excess of the equivalent capacity petrol engine. Stage 1 remap will give you 300lb ft, which is a lot! In-gear performance will be mind-blowing.
