Know the exhaust subject has been beaten to death, but I can't seem to find the answers I'm looking for via search. Anyone who has straight piped a 4.9, did you replace the first cat with a y pipe? While here: what size are the pipes going into the cat, secondly did you reuse the length of pipe with the AIR tube on it?

 

Nobody?

 

Probably because when you straight pipe a straight 6 it either sounds like a tractor or a pissed off bumble bee. Can't remember whitch

 

Honestly it sounds awful, but pipe size should be 2.5". Air tube never seems to get hooked up, not like its any use without a cat and now your O2 sensor has no where to go.

 

Please don't.

 

If you want to do it just do it and see if you like it. I bet you can find something on Youtube if you look long enough

 

What I did with my i6 is I cut off my muffler and all the cats except for 1. which I cut open and hollowed out and welded back shut. I did a true duals out the back. Welding the muffler is tricky so be patient. I love the sound its a screamer. I'm thinking about putting on flow-master super 44 but I'm not sure yet.

 

I ran mine with a glass pack for a bit and with no muffler for a bit, both sounded like crap and was very quiet, although I have both cats.

I found a flow master muffler with duels straight out the back at the scrap yard a few years ago, gives the truck a nice sound but is very quiet in the cab.

 

There is no O2 sensor after the cat, just the AIR tube. And i know it's 3" after the cat, I felt like it was smaller before.

 

96 yes there is an O2 after the first one.