I have had this truck about 4 months now, when I bought it the P.O. was running a flowmaster muffler with the 4 factory catylitic converters. I wanted more noise out of it so I decided to do some home exhaust plumbing, I cut the tail pipe off and started the truck with the open muffer under it with really no change so I cut the muffler off (where the cab and bed meet) and it sounded good but not much change at all... I was thinking it would be much louder than it is but I had suspected plugged cats since my mileage fell to nothing about 2 months ago. Has anyone straight piped with the 4 cats on?

 

A plugged cat is always possible if the truck is running lean, but the four cats also do a really good job of muffling the exhaust noise.

 

Put LT headers, and no cats on it. That will open it up. I did that and i didnt like the drone. So i put a excelerator x pipe muffler on and got a very very nice tone.

 

i run 4 catts with straight pipe. sounds good to me. but not very very loud

 

I used to get system lean codes randomly, I've been a little busy. I'll get a buddy to come over and help me video it and I'll give y'all a YouTube link

 

I was getting random lean codes on mine and my mileage dropped to 9.5mpg loaded or empty. After trying all the simple causes I eliminated all 4 cats and ran true duals from the manifolds back and now there are no more lean codes I've noticed quite a difference in power towing and gained 4mpg back. Now that being said I did a LOT of research before I ran the exhaust, I re-installed all 4 O2 sensors, down sized from 2.5 to 2.25 pipe and installed a magnaflow tru-x crossover to keep back pressure even on both banks with 18" glasspacks right in front of the axle. The end result was a nice throaty rumble without being outrageously loud and decent performance gains for a truck with 237,000+ miles on it.

 

You didn't get a check engine light from the O2 sensors with no cats? Tips and tricks on getting in there to get em cut off and getting the new ones installed?

 

As of right now I am getting codes for no cats but I'm in the process of getting an SCT programmer with custom tunes to fix that problem, as far as getting the cats off I just used a sawzall and cut them out it's pretty tight under there so watch what your doing I have a friend with a lift in his shop so it wasn't that hard to do on mine.

 

Or you could have just done a full tune up and your issues would have gone away. SCT tuners aren't cheap.

 

That is a good point, but I had already done a full tune up and top end cleaning. My problem was the upstream cats were clogged, I could have just replace them but there are other performance mods that I planned on doing that included the exhaust. I just installed the exhaust that I was going to go with anyways instead of having to do it twice. I do plan on getting some good performance cats to put back on it when I install the lt headers but that is a little ways down the road.

 

What tuner are you looking at? I'm going to order superchips vivid linq here soon, I'm most likely going to get 2 high flows. They don't do emissions test in my county yet but all of the surrounding counties do and the county is talking about requiring them. I thought about just hollowing out the old one's but I figure I should do it right while I'm at it or just straight pipe it. I'm yet to find someone to help me with a video in the daylight.

 

I plan on getting the SCT live wire for mine they seem to work the best on fords from what I've read. It is a good idea to go with the high flows but be careful on what you get just because it says high flow doesn't necessarily mean it is there are some real good threads on this site that can help you find what to look for in a in finding good high flow cat. I'm going to try and get a video on YouTube today so you can hear what mine sounds like with my set up before I put the headers and high flows on mine.