The key to more power is to get your engine working more efficiently to get the inlet charge (air and fuel) into the cylinders quicker and in greater quantity; and then to get rid of the exhaust just as quickly and efficiently to make room for the next incoming inlet charge.
Thats why the first power mods most people do are the exhaust and air filter. Youll hear a lot of talk on here that seems to go against the grain of whats recommended in the mags, thats because Clios like the 16v/Williams/172 have a lot of engine packed into a very small engine bay and run very hot. Induction kits for example are no good at all under these conditions.
However on a 1.4 RT as James proved today, there is enough room in there for cold air induction to be possible using an induction kit and also the engine itself doesnt run that hot. So first mod for you should be to get an induction kit and make sure you have a good chunky cold air feed from the front of the car. Next stop is the exhaust. You can start with just the back box if you want a bit of noise, or if you actually want power as well go for a cat back stainless system, then you can add a decat pipe later to complement the induction and exhaust mods.
Hope this clears it all up/
