There's a point where gaining any more power from this car will become increasingly difficult both financially and physically, and when I reach that point, I'll be looking to move on, onto another car, with more power to start with... And then soon, I'll be looking to upgrade that too... Ah.
Sure, you're right, I could do anything to this car, I could put a turbo on it, or a supercharger, nos, modifications to heads, valves, etc, but this would cost thousands and thousands of pounds, and would result in (my opinion, although I might be wrong) a car with significantly more power, but, surely, a lot less reliability than the stock car, and it would STILL be 9 or 10 years old and getting older, and by extensively modifying it, I'd just be asking for trouble where more and more components would start failing and need more investment to keep it all running.
An alternative of simply buying another, more powerful car to start with, seems much simpler (and cheaper too) to me, with more satisfaction to be gained with less hassle.
All that said, I still LOVE the "wolf in sheep's clothing" factor this car has, and you're right, it would be awesome if this car could do 5-6secs 0-60.
It's really not bad as it is, my friend's got a brand new Golf GTI, and he couldn't lose me one bit on the lights the other day. And he does know how to drive. 
i could end up spending time and money on this, and have even less bhp as the final result!
