What engine have you got??
You could start with the normal air filter expect no more than 5bhp for this.
Do you have a sporting??
If so you can fit the 1242cc SPI engine from a Punto 60 with ease.
Try looking at http://www.giwasa.com they are in Spain as well.
I've emailed me about there 1.4 turbo kit for the Seicento, should be interesting [:0]
"The Not so Fast but Furious"
Who cares about my post count - it's all about quality not quantity!!
(at least thats what i tell myself anyway)