ermm, seems like this topic has already been discussed 2 many a time...
nevertheless, i'll try 2 explain the 1st stage modifications (basics)... it is essential 2 know that a good performance car is built from ground-up. which means we should start with the tyres and so on.
wheels & tires: if u should fancy changing ur stock rims with new sports rims, remember 2 get urself good tires as well. tires' performance vary widely. it's a good practice for city driving to get a balance tire in terms of wet & dry handling. low-profile tires provide better handling while high-profile tires are for comfort. also remember that bigger wheels are normally heavier than smaller ones. heavier wheels increase the rotational moment of inertia n therefore causing the car 2 be sluggish. if u dun fancy changing the wheels nor the tires, skip to the next step...
brakes: get better brake pads with higher friction and effective working temperature to ensure ur car stops well.
suspensions: u can start by replacing the stock springs with sports springs. this will give u a lowered height n a stiffer ride. lower ride changes ur car's centre of gravity n stiffer springs lessens ur car's body-roll, both resulting in better handling and more agressive look. it is also advisable 2 change he stock absorbers 2 sports absorbers. this is 2 better compensate for the new spring rate.
intake: upgrade ur intake by replacing the original equipment manufacturers(OEM) air filter to either aftermarket drop-in air filters which can be fitted straight in2 the factory air box or opp out for unversal open-pod air filters(u will require an air ram 2 be fitted 2 the throttle body). with proper set-up (heat shield, cold air intake & what not...), oen-pod air filters would produce better horsepower. some of the good brands are K&N, HKS, Apex'i and Piper-X. these aftermarket air filters promise better air flow in2 ur intake manifold, thus increase the horsepower of ur engine.
exhaust: upgrade ur exhaust by first replacing ur stock headers(exhaust manifold/extractor) to an aftermarket tuned length extractors. this will ensure the exhaust gases will all travel the same length from all 4 cylinders, thus reducing back pressure resulting higher horsepower. set-up can be the form of 4-2-1 or 4-1 depending on ur preferrence of performance. a good muffler with less restrictions also helps the engine breath better, but 2 de-cat is not advisable as it promotes air pollution. i would recommend u 2 go 2 Powerzone in Glenmarie for enquiries.
part 1 of modifications has already been explained, other sifus pls continue with the next stage...