What would happen if I removed the cat and ran just the muffler?


Will I see performance gains? How about the warranty?


Thank you, Kent.

Probably performance gains would be too small to measure if any. You would be violating the law if that matters to you. Warranty would depend on your dealer, but I'd bet most would use that as an excuse to deny warranty claims. Do yourself a favor, buy a good sounding 4in or larger exhaust and keep the kitty.

I certainly have no regrets about removing my cat. Who knows if it helped with power or fuel economy. Maybe slightly. I know I'm getting better fuel economy now than I did with the cat still in place, but I've done other things as well, like switching to synthetic oil & using premium diesel, so who knows how much removing the cat helped. The truck definitely sounds & smells better without it, though.

deadfurrow what kind of mpg boost?

The biggest effect I saw was the lowering of EGT's. Worth it for that alone IMHO. A good 150-200 degrees.

Thanks for the replies guys, Kent http://www.dieselplace.com/forum/smileys/Clap.gif

deadfurrow what kind of mpg boost?

I use to average 18.6 MPG on the interstate while driving 72-77 MPH, depending on which state I was in. Over the last month or so since removing the cat, switching to syn, & using diesel supreme, I'm at 20+ MPG average interstate driving. I actually got 21.66 MPG on a 327 mile round trip to Cincinnati on Wednesday, but I didn't use the a/c any & there was hardly any wind. It's almost like the engine is still "breaking in", & it has 47k+ miles. I can't explain it, but I ain't complainin'!