personally, id pick bikes everytime. much lighter, much faster, and now the jackpot answer....much cheaper.
but i have seen a corsa 1.2, still badged as such, stock outside, steelies etc, but with a 400hp audi quattro 3.2 engine in it. didnt see it go, but my god it sounded mean. the only way you could tell is the race buckets and the side exit zaust