I didn't find I was down on power without a cat. What I found was, I could smell gas in my exhaust. It didn't just smell like... Exhaust.

 

...Sounds like you may have other problems ??

 

Nope. As soon as I threw the new cat on, my mileage went back up and the exhaust smelled better.

 

When you removed the old cat did you just hollow it out , or did you put a new piece of pipe in ? , your old cat may have been clogging up , the bottle neck in these trucks are the stock exhaust manifolds back , so just removing the cat won't help much , free flowing exhaust will help mileage not decrees it ....

 

Removing a catalytic converter should boost your MPG. If yours fell, you have definite underlying problems. If your exhaust smelled different, it's because you removed the filter that took out things you didn't smell before.

Also, to whomever said "go by your state and county laws" about the catalytic converter, the state and county laws will be no less strict than a federal law. Here in WI, a vehicle with Antique plates are for 1945 or older models that are unaltered. Collector plates are 20 years older, and unaltered. However, a "Hobbyist" plate can be issued on a 20(+) year old vehicle and allows you to alter the vehicle from factory specifications. This does not let you alter the emissions however because that is a federal law. Hopefully this can clear up any confusion about what you can do with that. Keep in mind, that you are allowed to replace a catalytic converter, and as long as you meet the emissions standards that your current truck has, you can use a high flow catalytic converter.

As for whatever LMC has, I would just take the truck to a shop that does exhaust and have them do it in stainless pipe. There are shops around me that can put exhaust on for less than what I'd pay in pipe and welding supplies to get mine done.

But anyway, you can run whatever size pipe you want, and you didn't say what motor you have, but if it's a gasser small block, 2.25" for duals minimum is good, and 3" for single is plenty. On a gasser big block, 2.5" duals minimum, 3" is better.

 

Also you want to make sure you get mandrel bent pipe , the pipe benders will change your pipe about 1in less at every turn , thats no good , custom made exhaust is the best way to go ....

 

....So your one of the few that think ford did a good job on the exhaust on these trucks , thats ok , i think there is a lot of room for improvement , why no make it better when it needs to be replaced anyway ??

 

I feel they did a decent job. For me the system works and I haven't had issues. Steve83 @ Supermotors has well over 500k miles on a stock, never rebuilt engine using all stock emissions components and exhaust. That's enough for me to stick with as close to factory as possible. I do however feel that there is indeed room for improvement. However, from what I have seen online, many people that have decided to tear the old out and put new in have faced issues with there modified systems. I feel if you deal with the emission properly when upgrading the system, you can indeed make it much better. For me, where I live, they check for all emission and they must be working. This doesn't give much room for modification.