Nice looking car.
Regarding performance mods, some things will be good value (handling, looks, sound, etc) BUT trying to wring more power out of a small-displacement 4 cylinder naturally aspirated engine pushing a heavy AWD car is going to be a very inefficient use of your time and money.
If you like the car and will hang onto it for a while, I recommend focussing on the "bang for buck" improvement areas. If you really want more power, make a plan to get a turbocharged or large-displacement (or both!) car and put your money towards saving for that rather than modifying your Liberty.
Also is worth putting cold air intake system on? I know it doesn’t do much for the performance but it does sound good.
Should I go for it or not? If yes what brand you guys recommend?
A lot of so-called "cold air intakes" are just pod filters in the engine bay - with or without some sort of ineffectual shielding. Hot air is counter-productive to performance because the air is less dense AND the ECU retards the ignition timing (as knock prevention). If you just like the look/sound and can handle the loss of some power maybe this is ok for you.
If you find a commercial off-the-shelf system that genuinely draws cool air because the air filter is isolated from the engine bay then you can consider it on its merits - including price!
A lot of people get a better intake sound by removing the resonator from the factory airbox then extending the resulting hole with the use of pipes to a cool pickup point.
I used alloy and silicone tube sections (see this page of my build thread
viewtopic.php?f=10&t=36234&start=15 ) but others have had success with Bunnings-spec PVC pipe.
I've done something similar with a naturally aspirated car before (3.8L commodore). They do sound better and draw cooler air. The down-sides include the need to change the air filter more often (depending on air pickup placement) and a load of "experts" whinging at you that the engine will ingest a load of water and die (which has never happened to me - after a torrential rain freeway trip the only thing that happened was a soggy air filter).
If you want the better sound and don't care about hot air, just remove the resonator from the airbox and leave things at that.
Good luck with it whatever you chose.
EDIT - For the sake of completeness it is worth mentioning that intake resonators are sometimes for noise-reduction, sometimes for extra power (tuned frequencies etc) and sometimes both. Such features can be important on a naturally aspirated engine. "The internet" will debate until the end of time whether (eg) removing the resonator will affect power in a given car. Nobody seems to have the budget for comparable dyno runs except for "buy our stuff" manufacturers whose results should be treated with caution.
If you make your resonator removal (& perhaps replacement with piping) non-permanent* at least you can swap things back if you don't like the modification.
My guess is that nobody would notice any slight loss of power that may occur at
n,550 revs because the resonator has been replaced with a secondary cold-air feed. The "sounds better" psychological kilowatts would make up for it
(*either with original parts OR by getting an unmolested airbox from the wreckers when you want to swap things back).