You can get the piper cam for it and it helps breathing in the mid and top end up to 5500rpms
also you can get bigger injectors for these but they are very hard to come by, and the 2.2 injectors won't fit, I believe the injectors are called AMG injectors and thats not merc amg, but i'm pretty sure thats what they are called
an intercooler with an exhaust with a decat (the cat won't be required to pass an mot on that engine) and a decent induction system and a remap will get you to 150-160 bhp but you also need to get an uprated clutch, best to get an from helix
the k04 would be far too big for that engine, something like a gt17 would be more suitable as an upgrade but at 150 bhp the injectors are running at the maximum, however I do know that those engines will take up to 230 bhp,
What I would say to do after you intercool it is to get some water injection and lpg in there, and also an LSD is pretty much essential because it will be running around 260-270 lbft and even a stray onto a white line without one is enough to spin a front wheel, also running lpg will make the camshaft more beneficial as the lpg will help access some more top end poke, but it will be limited to the size of the turbo, turbo dynamics and turbo technics both do a hybrid turbo (gt15/17) for the hdi 90 and thats the best way to go