am in the market for a vrs oil burner but am not sure which one to go for i would like a CR but think the wallet says it will have to be more of a PD has anyone used one of the tuning boxes you can get? are they any good? what do they do to the MPG?and also does it make the power delivery more linier and more "CR" like?

I am tempted to get a PD as its a fair bit cheaper and stick on a tuning box if its worth it?

I wouldn't bother with a tuning box, just get a remap instead.

The CR is more refined and the power delivery more *similar* to a turbo petrol engine than a turbo diesel. The PD gives a greater thump lower down but tails off earlier.

Common Rail is definitely the route to go if you like refinement.

The 170CR is so smooth & quiet it's unbelievable, it's worth the extra cash if you do the miles.

Having owned both, the pd covered 30000 miles, the cr is sitting at 11000, I would say the cr is better.

It is smoother, quieter and the economy is a good 4 to 5 mpg better.

There's a reason the CR engine replaces the PD one - it is better... Don't bother with tuning boxes - they work by lying to the engine by falsifying the data it reads from the sensors, leading the engine to think it's cold all the time and overfueling it. A remap changes the OEM software that runs the engine to better software. Just make sure it's a reputable remap.

There have been some reports on this site recently of CR engines developing serious vibrations at about 18K miles which dealers are having problems solving. Worth looking into before buying a CR engine maybe.

Also dont bother with tuning boxes, go for a proper remap if you are intent on upping the engine performance IMO.