I drive a 90 supra, and am looking into buying a new exhaust. My current one is a dual tip, but i dont know the brand, It came on the car when i bought it but it says 3R Racing or 3A Racing I believe. The problem with it is its really really loud, luckily i havent been pulled over because of it, and i dont really like the look of it, although im a fan of dual tips. I've been looking and so far I like the apexi n1 and the raptor racing modified magnaflow. Im a complete noob when it comes to exhaust, and planned on having it installed at a shop either way, so thats not a problem. But my question is whats the difference between buying only the muffler as opposed to the whole cat back system/piping? Am i likely to run into problems only buying the muffler instead of a whole brand new system? If I bought only the muffler it would still change the sound right? Any Pros/Cons?