the thread on xpf is for my car, and tbh the best place to look for L-series tuning info is either on .org or
http://www.roverdiesel.co.uk/
reliable performance on standard parts is about 150bhp and 250lbsft that is 50% power increase and 25% torque.
to do that you need: SDI injectors & remap (i recomend matt reidy)
to help keep smoke down you probably want to change the induction and exhaust.
As soon as you try to get more the L-series decides it wants to get thirsty and will drink your coolant.
i am loathe to quote figures but mine could be around 170bhp possibly more (probably less) and upto around 300lbsft torque - but again probably less as I will probably go conservative on the map when i take it to Matt.
Would rather have the car on the road for a while than to get bragging rights with the figures - I say this cos we done know for sure quite what the headstuds will be able to cope with.