The noise you are describing is the noise of the tappets/lifters, it's basically a Mitsubishi engine trait and happens because of a number of reasons.
Slight ticking at idle is ok on older cars like the FTO and sometimes it can't even be eliminated without swapping the lifters.
Some things to fix the ticking if you get sick of it would be to try various grades/brands of engine oil, I find in some cases that older engines despite being the same will like a different oil, so keep that in mind. Another way are additives to your fuel which will fix the problem for about 5k. But remember if either of the two work then you may still get ticking on idle when giving the engine a decent workout.
If that doesn't help then the lifters are adjustable only on the GPX versions, the GR has hydrolic lifters which are meant to adjust them selves, but even a clean may help. Adjusting and cleaning are best left to a major service as the mechanic will need to take the intake manifold off.
Anyway there is a ton of info already on the site so do a search if you need more info.
