Ford focus tdci how to make it look good?

Gettin a focus tdci 04 black 3 door
Just wondering how can i make this car look a bit COOLER i'm changing the muffler even though its a diesel to make it a bit beefier, might add a dumpvalve, new speakers, subwoofer and amp,
What else can i do with this car

Burn it.
Seriously, if you want to boy racer a car you couldn't have started with a worse one than a Diesel Focus. A chav back box will sound horrible with a Diesel engine and a dump valve will do absolutely nothing.
Service it and fit a decent stereo and leave it at that.