I am thinking about replacing my exhaust system on my 97 accord lx. I like the apexi ws2 mufflers. I do not know what diameter piping i should get for my car. i do not want it to sound loud and i am not going to do any major upgrades to the engine besides CAI and headers. my goal for the car is to keep is runnig smooth and responsive while upgrading it mainly for better performace. i know Apexi has a cat back system, but i do not know if i am better off just buying the muffler off ebay then taking it to a muffler shop and having them make a custom piping system for the muffler. i want to replace the catalytic converter with a hi flo cat, but i live in california and they are very strict on emmisons. i have not yet purchased the headers, downpipe, cat or muffler and i am trying to match everything so i can get the best performance while keeping it sounding close to stock while driving around the city. Car currently has 200,000 miles and still runs smooth and quite, ive replace a lot of routine things on it and it has never broke down on me so i have no problem putting an exhaust on. trying to get it to 300,000! any advice or help would be appreciated

 

2.25inch piping is a common DD size.

 

2.5 for dd is ok