Hi and welcome - are you gonna supercharge it??
I think the cost will outweigh the benfit. As an example, spend £10k on a Skyline and you get an extra 200bhp. to get a Clio v6 to say 350bhp, you need to spend £10k. Tuning a car that has an engine designed to take a turbo or supercharger is better.
Having said that, I have seen the Clio 182 with the Turbo conversion and its bloody quick.
My idea was to try a turbo set up, but have since found out that I may at most be able to push in 0.5 /0.6bar of boost pressure before the head and inlet gaskets give way.
The cheapest way would be to use NOS, but I am not really a fan of this. Other option would be to take out the 3.0V6 and put in a turbo charged Audi TT engine - A Clio TT! This conversuion would cost again say £10k, but then you have the possibility to get 400bhp
Nik