I have a 1990 ford bronco with the 351, I was just wondering what the deal is with the 2 cats under there. Why 2?

 

 

I have 2 cats on my 88 F-150 with a 302, and as far as i know, they did it for emissions, so it would burn cleaner. My dad's old 82 with a 302 and someone had cut the cats off and it passed emissions. I don't think that the second one is too necesary, if you want to cut it off, you should still pass emissions, but your best bet would be to talk to a muffler shop, or the person who does your emissons. Be sure to check any federal/state exhaust regulations before cutting anything off though. It can be a $10,000 fine or more.
-Shawn

 

The front one is a pre-convertor and the rear is the actual catalytic convertor. The first one heats the gas going into the convertor so it will burn cleaner. I read somewhere that our trucks only burn about 60% of the actual fuel and the convertor burns the rest. That's pretty poor on the engines part.