well like its other small block 16v brethren, the inlet is pretty restrictive, a mantezl power box would be good, coupled with a unichip and a decent exhaust, would give you a decent power increase
tyres suspension are a must. my 1200 nova on coilovers can just about keep with me brothers 1600 16v through the twisties, he tears away on the straights but i dont half catch him on the bends cause i can carry so much more speed round them.
Ive recently just fitted a Dbilas inlet manifold to my 1600 16v corsa and it has made a reasonable difference. I didnt buy it with the chip tho so hopefully when i can afford it i will get that aswell because i have to admit i did expect more of a power increase.