Slight improvement in fuel consumption, slight increase in noise, I prefer to hear the engine on my cars, and a little cough on overrun to add to the character. Shortening the air inlet really helped initial pickup as did de-restricting the airbox and changing the air filter for a free flow type. The best intake design for a N/A petrol engine is not the best design for a turbo diesel, so some research on turbo engines led me to the solution I have.
Finish with remap and EGR delete to maximise reasonable potential and clean up the emissions by no longer having to chew on its own effluent and I'm pretty impressed. Once warmed up, I can now cruise at 32mph in top gear with no juddering. Smoke test was very good 30ppm at full throttle and sit at 70ish on the motoway in top and floor the throttle and I think a 3.2 would struggle to keep up.
One or two words of caution. Not every car responds the same way, mine seems to be much happier but there's no guarantee others will and, you may find you are at the torque limit of the clutch, and hence also quite close to the torque limit of the gearbox too.
Is it worth it? Yes absolutely for the improvement in refinement and performance but like everything it has to be done properly by clever reputable people and does carry a small element of risk.