if you have the same open air filter as that car in the link then bin it and either put the standard airbox back on and fit a panel filter in, or buy an enclosed filter such as the bmc or the green enclosed. then you're looking at cams+ headwork-port/polish bigger valves (or you could fit a c2 vts head, bit more work involved as you'd need the saxo inlet+ecu, remap, then throttle bodies or boosted.