The only problem with a 1.1 is that you need to do quite alot before you get anything from it.
Ideally you should just keep it tidy, look after it and don't rag it.
Then when it comes to moving onto a new car you havn't lost loads money by putting on pointless bits to the car that make it off putting when it does come to selling.
If you are desperate for more speed then take out the spare wheel, all panels, rear seats etc etc. They can be put back in and costs nothing but a bit of time. Improves all aspects of the car too, accel, braking & handling.