you can go 35mm on the front, which is actually 55mm lower than an rt! on 15s you will need 45 profile tyres, the 16v is good cause of the wider arches so there is more room to play with, but the idea is to get the center of gravity down but not too hard, too hard and you will loose all grip in the wet, this is why i recomend the pis, their not to stiff but still give good handling ij the dry,
will try and upload a piccy of our demo car on pi springs
Dave