I'm gonna tell you what you won't like to hear: Don't bother.
To achieve real gains on an NA engine, you either:
- need to be lucky to have a very restricted engine that can easily be restricted (not the case), or
- have to do some serious modifications and changes to the cylinder head, which even gets expensive IF you can do it yourself, let alone when having to pay hourly rate.
Changing the intake and exhaust can deliver marginal gains, but those are really nothing for the cost and added noise you are getting.
Unless "0-60 is life" or the car is really slow (which a 1.4 16v Punto shouldn't be), proper handling mods are what actually increase driving pleasure and makes the car safer as well.
I'm talking:
- lightweight wheels with good tyre, something like 6-6.5" wide 15-16" alloys with 195 wide Vredestein/Michelin/...,
- shock absorbers (Bilstein f.e.) and subtle new lowering springs (Eibach f.e.), don't be tempted to "schlamm" the car on adjustable coilovers, you never get them right and there is such a thing as too low.
- Rubbers and bushings, simply replacing old by new, or upgrading them with polyurethane ones.
- swaybars: thicker, stiffer ones make the car lean less over in corners, make sure to upgrade front and rear equally unless you want to change the oversteer-understeer balance.
- brakes: pads, lines, fluid...
- ...