Allright mate, I have a 1.8i Cav, they are not the easiest car to tune but I have done the following to gain about 15-20 bhp - 1.Scorpion Cat Back Stainless system - £300 but good improvement in throttle response & better breathing top end.
2.K&N Panel Filter - Better breathing & throttle response & noise but am going to replace with 57i (£70) as these work very well on the 8v
3.High-Lift Cam- (about £150) Slight loss in power at low revs but a good kick of power over 3500rpm ( these can be difficult to source but are out there).
There are a few other things that can be done eg, Cylinder head ( around £300 - not cheap but worth it if you`ve done cam etc), junk the cat ( £70- just put it back on for MOT).
I don`t think you can chip these engines & have heard a few bad things about those ecotek valves.