You should be getting 200-210 (at the fly) with the TTE charger. You seem to be getting very little over standard. It sounds very much like you are loosing boost.
Check the entire system for leaks, as you may be loosing boost through a badly sealed join in the piping between the air box and charger, charger and intercooler or intercooler and inlet manifold. Also check that the belt is in good condition and tight, as they can slip. If in any doubt then replace the belt, I paid under a tenner I think.
The best thing you can do it rig up a boost gauge, that will show you when you are loosing the boost.
As for further increasing power (after you get this sorted, of course) your best bet is to remove the pre-cats from the manifold, the main cat too (though you will probably have to refit it for MOT time), Denso iridium plugs are good, and either an uprated air filter or preferably an induction kit (sounds absolutely awesome, nothing like it on this world, though wouldn't recommend it if you want to be subtle!) That's about as far as I got with mine! You can't really tune it much further without going into BIG money thou.