The front cat on my driver side (2001 F150 5.4L, 150K miles) is rattling real bad. I confirmed that the the internals are loose by taping it with a rubber malet. It clearly sounds much different then the other 3.

Question #1: If I replace it with an OEM style bolt-on (Eastern Cat- $270) do I need to replace the passenger side as well. Right side does not rattle, but will repalcing left cat with a new / different manufacturer cause any sort of imbalance?

Question#2: My other option is to get a pair of Magnaflow 94106's. I have never welded exhaust components, but have some sheetmetal welding experience from some other projects. It does not look too complicated, but in most all of my searches I see recomendations to take it into a shop to have them fitted. Any reasons why I shouldn't attempt to weld myself? I have a small mig, I know a tig would be ideal, but I am not to concerned with pretty welds. Any Thoughts?

 

Order magnaflow and take it to a shop. If your not a good welder, you WILL end up with leaks. I am a welder and I recommend taking it to a shop. Welding pipe is nothing like welding sheet metal.