There are big holes in my knowledge, but AFAIK Stage 1 wont really do much on a Clio 16v in terms of outright accleration.
Because of the small, hot, engine bay induction kits do little except add a really meaty noise (probably the best on a production hatch); similarly with the exhaust I suspect. The chip should iron out flat spots and increase the revs you can get to - which, since the maximum output on a standard engine is c.7000rpm, will usually only mean extra power if the engine is modified to develop more power above or at the standard rev limit of c.7300rpm.
So, Stage 1 will make the car more driveable and make it sound fantastic - but shouldnt see a Clio 16v make much clear extra power. I guess its a preparation for Stage 2, where the benefits of breathing and extra revs really will combine with the additional mods to increase power/torque/accleration.
The 106 GTi is a very quick car for reasons that are not always easily understood - not least by me! The Clio 16v barely weighs any more - maybe 50kg at most - and has about 140bhp per ton. Meanwhile, the 106/VTS have c.125bhp per ton and less torque. But they deliver the power in such as way that they really impress/embarass up against other hot hatches. You could start to close the weight gap by leaving the spare wheel at home.
Having just changed from 16" wheels myself (back to Phase 2 15s with 195/50/15), I am also of the opinion that the initial acceleration is a bit better on the smaller wheels - provided I dont get wheelspin.