Hi Stuart - what increase in performance have you gained by fitting the air intake and the back box and how much money do you want to spend. Have you notified your insurers of your modifications and what extra - if any have they charged you.
with all the electronics in modern cars there s only one thing left to tune - get more air into the engine and the electronics should (if in limits of input data map) give you more power, anything more -> buy 2.0 16v or at least 1.6 16v
I agree Dijan - he should save his money and get a more powerful car as in all honesty there ain't much to work with on a 1.2 Litre engine. I find it strange - many people tend to buy a small engine car for economy and insurance reasons and then want to lash out loads of lolly to make it more powerful and thirsty and if they don't inform their insurers and have an accident whinge and moan but when this happens it is actually the honest everyday driver who pays the price. My mind really boggles at times
If you want to go faster, take everything out of the car you do not need ie. put the car on a diet.
Say if your car has 65bhp and weighs a ton you have 65bhp/1ton if you drop the weight to 900kg you have 72bhp per ton, so it will cost sod all but power to weight ratio will have risen by 7bhp and it aint cost you a penny!
To be fair you would be lucky to get a 1.2 say with 65bhp to any higher than 71-72bhp max, and that would be with spending prob £700+ or so ie new manifold, de-cat, system exhaust, a good cold air induction kit, and a remap or chip.