There are more but no offense you could do the research yourself, might give you some ideas on what you can do on the fusion.
I myself was thinking about removing the muffler, but I'm not sure right now. Worse the would happen is cut the muffler off, drive it, hate it and weld back on. only thing it would cost me is the gas to go up to my uncles. He's on vacation right now anyway.
It's illegal everywhere [think Federal Law] unless the vehicle is not "road-worthy", ie a track car or funny car. Deleting the cat will increase HP at the loss of Torque. You can get an O2 sensor "trick" harness where the ECU thinks the cat is installed and working fine, and they are about $50. With this harness, you will pass an OBDII scanner-type of emissions test but obviously fail a visual inspection. The car will run fine. As Crystallas said, it will be significantly louder. Best gains will be had with an entire high-flow aftermarket exhaust and a tune. You gain very minimal Hp with this mod only. Best idea is to buy a Random Technologies universal high-flow cat (to keep it legal) and the magnaflow exhaust.
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