For the amount of effort it takes, plus the extra insurance cost, it would be cheaper all round if you sell the 1.4 and just buy a GTI 16v, or an 8v GTI if you're young and not used to anything THAT fast.
To be honest i only got the golf because a family member selling it cheap - im currently driving a vxr astra which im sure is fast enough so the speed isnt a worrie 4 me - i had a nova with a c20let last year - so was wanting to put a faster engine into a differant shell if you get what i mean - thanks ha