petroleum

hey everyone, just bought myself a ke30 rolla... only paid $100 for it.. but its good the 3k motor was taken out a year ago and replaced with a 4k and a 5spd transmission, new exhaust (tiny)... anyways is it possible to replace the leaf springs in the back with coil springs and shocks?... also wondering what i can do to make it go faster... going to get my hands on some extractors but i'll need a good carb but i also need something with good fuel economy... any ideas on what the best is? basically the whole car is stock and i want to make it better :) thanks people!, dave