to have a supercharged Fiesta running about 300BHP that you wont need to worry about going wrong you will need

forged engine incuding bearings about 1k to do properly
LSD + MTX75 gearbox another 1k+
clutch about £300
SC kit fitted about 4k
and you will need the cossie cams, the mountune cams are not harsh enough £400+ fitting
you need coilovers for proper grip £500+
polybushes £400ish fitted
brakes at least £1500

the prices are all new parts obviously i looked into it big time with my old fiesta before i sold it

£9100, but with fitting for everything an easy 10k

when i looked into it i wanted to do the lot as i didnt want any problems, everyone does each bit in sections then it goes wrong so they do the next bit and so on, then they sell the car because it costs too much or it keeps braking, i use my car every day so can afford it to be off the road