I just got this car that I wanna spend some money on (say about $2k-$3k) for better street performance but I am wondering if it would be worth it if I'm willing to stick with this car for a while. Now I already got some stuff that I listed below and I also had in mind to get a header (seems very hard to find for this) and set of wheels. I went to this Hi-performance shop and the guys there suggested  adding a turbo charged motor in the car and switching to manual transmission. So what I need now is some advice on what to do next looking at those things.

03 Mitsubishi Lancer OZ Rally FWD
2.0-L 16-valve four-cylinder @ 120 HP 130 Torque
4-speed Automatic
Magnaflow Performance Exhaust
K&N Cold Air Intake  

My friend, unless you want to spend more than what you're willing to spend... get another platform. The ride you have is a very good ride as an every day ride. once you start messing with it you destroy it. The advice you've gotten so far form those shop guys is pretty much on point. The stock equipment will need to get swapped out and that means some money. More than you seem to want to spend. I'm not saying not to build it... what I'm saying is what are you truelly willing to spend? Be realistic in your endeavors. How much can you do with what cash you have? How much of it can you do your self? You see? I have my own shop and employ some 15 guys so things like that are part of my every day decision making for the customer. Think of what you want and plan for it. I recently finished building a RB26DETT for an old school ride that I own and, because of my lack of body work knowledge had to get some one to replace my fabricator/body guy to finish the job. It is costing me some money but it's worth it just to get it done right. Money makes things happen.  

lets say I am willing to swap out the critical stock equipments needed to not mess up the car, what stuff am I exactly looking at and how much will the cost be around?  

nah keep it stock, the oz rally is pretty nice handling man....the rear sway bar gives it some nice  movement, and its waaay more enjoyable than an ES, trust me, if you want some more power, you can just put in the KN intake, KN intakes r good trust me, and exhaust if you want, also get good tires, i sugegst yokohama's because you can get some pretty good quality but cheap ones.  get some better springs (H&R" good quality and cheap as well) thats all i rlly suggest, trust me the engine stock is good enough to give you the fun you want and the handling for an fwd is NIIIICE so i suggest if you have the money, focus on handling and suspension not on the engine, but dont spend too much money cuz it isnt rlly worth it. OZ rally's are pretty solid stock, but just dont think its a mini evo cuz its not. its just a fun little car, very fun nice car. keep it mosly stock, dont go crazy!!  

ya some other guys gave me an estimate of adding a turbo kit at about five grand which isn't worth it so I'm not going for that but I am getting some good quality 18" tires though that seems worth spending money on for the looks and stuff and I already got the intake and exhaust system, so you think thats about all I should do to keep it safe and solid as it is performance wise? Would adding performance headers to it be a bad idea?  

no headers, thats good enough, trust me, when you start replacing stock parts like that, each time you find out you need to get something else for it to work well, then you find out you had a problem with something and your nwly installed part wont work because you are missing something and it keeps going on and on and on, so dont go crazy cuz itll make you spend a lot, when i got my air intake i had to go replace my fuel filter and a simple new exhaust tip meant i had to get a whole diff pipe, you get my point. You have a good car so dont worry, enjoy swinging it around man!!  

Hey miamito616, kinda' missed you there for a while. glad you're back. And you are extremely correct about that. Once you start messing with things like that you always tend to find out that it doesn't get exactly what you expect and that it requires more to make do what you want. I.E. More air requires more fuel and all that you do for those upgrades requires better exhaust exit. That's well over the $3K you're willing to spend right there. Lets not forget upgrading the pistons, rings, crank and a new higher volume oil pump to handle the extra power that the first upgrades give, even if it doesn't get you extreme horse power. Remember that with more horses ther is more wear and if you don't up grade accordingly to your expectations it can get costly and give you maintenance headaches. It's not just about slapping on some stuff and expect it to function as advertised, you know.  

hey thx for all the advice guys. I just hate it when my friends are putting me down saying I got a shitty deal trading in a 03 mustang gt for the lancer oz rally. Evos were always my favorite car but it was out of my reach yet so I decided to get a lancer and when I drive it feels lot more stable handling and fun than the mustang so I dont think it was a bad trade. So now all this upgrading was about showing them off that this car can be something too without understanding what you guys explained but it makes sense. Maybe once my credit is built up I'll be able to trade this in for the evo in the future but for now I'm loving this car as it is.  

If you plan on getting that monster of a car, remember also that most car manufactures make those cars for dealers but with out warranty coverage. The full race 350Z that nissan makes is a good example. Good luck and keep it simple and within your pockets range.