What is this? The 106 1.1 tuning club?
Just kidding guys, glad to see you've got the right idea with some of the mods!
Personally, I wouldn't bother with any serious work on the lump, such as cams, or even a s/s manifold. These would be great on a 1.6 but you wont notice enough difference for the money you'll be spending.
I think you've hit the nail on the head with the 'fuel pressuriser' (I've never heard it called that before!!), they are known as 'FSE Boost Valves', and like you say, they increase the pressure of the fuel in the rails, so there is more going through your injectors when you need it. This would compliment a decent induction system very well, as you can imagine, you need to balance out the amount of air with fuel (roughly), to maximise combustion..
Something else which may really work well for you is a 'Free Power Unit', the Peugeot/Citroen specialist GMC make such a unit. It works on the principle of disconnecting your alternator when you need power. As you probably already know, your alternator works off a belt connected to your engine, and uses the power created to charge your battery. This is always on when you are driving, but works harder when more electrical devices are used. You can feel the dip in REV's as a result, when your engines fans come on, or you use your electric windows.. The GMC unit works off of your 'Throttle Position Sensor', when you open up the throttle wide, it disconnects the alternator, so it is no longer sapping the power from your engine, and it goes straight into your drive system and onto the road, just when you need it!
Hope this helps!
Freddie.