Currently my 91 gt stang has it's original cats and muffler. Tomorrow I'm looking to upgrade with flowmaster 40 series and Magnaflow cats. It currently has the H-Pipe. My question is... can I get away with only using 2 cats rather than the 4 that's on there? Will it screw with 02 censors and effect my computer? I was hoping to go with 2 cats and 2 flowmasters. Any thoughts?