21,000 mile service intervals were introduced at MY2008 and I understand that dealers reset the ECU for earlier cars when they are serviced to the new interval.
Remaps should give 175 -190 bhp on a 159 depending on who does it and what your requirements are. It has been reliably reported that the standard engine when run in gives just over 160bhp anyhow. Dyno results posted on the Forum have been around 163 bhp.
AFAIK there is no particular history of premature cam belt/water pump failure. The service schedule MY 2008 on, states that the timing belt should be changed at 150,000 kms or 4 years - and it wouldn't make sense not to change the water pump at the same time.
Hope this helps
This is interesting, as the service schedule to change the 1.9 JTD cambelt in the 156/147/GT is 5 years (or 72,000 miles, whichever comes first), whereas with the 159 it appears to be 4 years! Now the main issue emerging in the JTD waterpump sticky thread in the 147/156/GT lounge is that premature failure of the waterpump (leading invariably to cambelt failure) takes place on average at the 4 year point! Obviously this is an approximate weighted average but consensus would appear to be a must to change the cambelt/tensioner/idler/waterpump/coolant at least at the 4 year point and 60,000 miles, whichever comes first.
Since it's the same waterpump for all JTD 1.9 16v and 20v engines throughout the Alfa Romeo range (147, 156, GT, 159, Brera and 946 Spider - Alfa Romeo Part Number 46804051 as verified on ePER), I would have thought it an absolute must as well to change the waterpump when doing the cambelt at 4 years?
Unless, of course, there is something else going on with the new range of 1.9 16v and 2.4 20v Alfas that isn't leading to waterpump failure??? If this is the case, can anyone suggest what this may be?