How's your intake? Mine was fairly clogged when I got the car but a good clean out and new air filter really helped especially up the revs.
What is you want to get from it though? Why not a remap or bigger injector nozzles or both? The bigger injectors have given me around 20-25 hp and a good dose of torque, well worth it to me. I do intend to get a vnt turbo and tune at some point too. I don't care that my car is older, it's been really reliable, I get 45-50 mpg while still driving between 80-100mph, I don't have to put up with a crappy dpf or any of the other modern gimmicks that seem to cause so much trouble. Yeh tuning boxes are a bit pants, the evry mod is much the same thing but a lot cheaper but if you want any decent power gains then you're going to have to part with some money. Injectors, remaps, turbos etc. It's the only way to get anything worth having powerwise.