Do-It-Yourself Garage

Hello to all... just out of curiosity, I just wanted to ask (recommendations) and know which of the car mod shops in Bandar Sunway are better at modifying K-Cars... I drive a Kelisa and am planning on changing the air filter, piping, and the muffler... I'd also like to know (opinions/estimations) how much I'm looking at "coughing up" to modify these parts of my car... but basically I'm not sure on which shop to visit and that would also perform good modifying job on my car... thanks in...