Gotta love a sleeper. As said, you could abarth your KA.

But an engine swap would be a winner. Relatively straightforward on a mk6 fiesta (previous shape). However, i'd start with an ST and change the bumpers to poverty spec items, fit steels and remove the spoiler, change the seats etc. then you could turbo or supercharge it. About 5k for a nice example of the car (need red or black really) then you can drive in and out of a tuners with the engine mods, such as Jamsport etc.

(edited to make sense)