What kind of performance mods have any of you made? You know like air intake changes, chip mods, anything like that. I just am curious since it is more of a tuner thing if any of you guys/gals have done these things.
Which model montero and engine are you talking about?
As far as air intake mods, unless you're talking forced induction (turbo, supercharger) the changes are nominal and in some cases you will see a decrease in performance. Chip mods are available but not simple to do since most I've seen appear to be complete ECU upgrades versus just a chip.
Engine swaps abound.
2.6L > 4.3L chevy, 2.6L > 2.6L turbo, etc.
Forced induction upgrades abound.
Turbo's, Superchargers, etc.
K&N & other reusable oiled filter kits? Don't waste your money unless you are doing it on a street only machine and want to benefit from buying cleaner kits versus new paper filters.
Again though, until we know which mitsu 4x4 model and engine you have, can't really provide more specific ideas.
Also, you should just create a signature and publish it with your posts like I did below so we don't keep asking you which rig you're talking about.