Alright mate,
The most noticable thing you could do is either go for the conversion to the 172/182 engine or do the twingo rs 133.
However thats not all you can do obviously for a noticible difference
i have a 1.6 16v phase 1 and ive found quite a few things that would and when all put together could give you quite a gain.
panel filter and cold air feed (this seemed to give me a smoother drive than my induction kit) so K&N Panel filter with a cold air feed which is running to my fog light. (No bends in the pipe so its going straight there.
Also ashley exhaust system, im not sure weather this did much until it got decatted the other week but im sure it has changed something (small)
If anything different exhaust-decatted onto a after market manifold (Ktec offer one of these but they arent cheap).
http://www.k-tecracing.com/show_product.asp?id=381&appid=4
After you have done small things like this then go for your remap, well i would personally but thats my own opinion.
I think the remap alone gives something like 7-10bhp? but as said if you do all of the correct things you can still get some performance out of it without going for the major swaps!
Just check out ktec's site (follow that link to the manifold) and see what you can find on there!
there is all sorts of stuff.
Ps i would reccomend the ashley exhaust and decat pipe as when decatted it makes the nicest sound out lol
hope this helps you out abit!