So, after 325,000km I cut out the cats on my '03 S'crew. Making a long story short.............. its now a bit noisier, but my milage went up by approx 6MPG (maybe more) and it feels like I gained a few HP. The top cats were almost plugged completely and the bottoms werent far behind. I have no "air care" so there isnt any issues and the truck runs fine. The new engine can now take advantage of the balance of the goodies I installed when the new engine went in.

 

Yea right. Long story short. - They are not tuned to run this way and unless you have a custom one, that truck is falling flat on it's face as far as low end torque. Probably drones at every speed and like you said, you could care less about pollution.

That was brilliant.

Sure, you may get better mileage than you were with defective converters, - no brainer, just like the rest.

Cool mod buddy.

 

I'm about ready to get rid of mine... They smell horrid when I get on it and it's not loud enough!

 

You'll need a tune for it. If you just off the rears and run the smaller upstreams you won't have to tune; your still within parameters. All of them is the problem. I've never seen these plug in with material, but it's possible w/carbon. I've seen plenty that melt and close shut in a perfect circle from running additives lol. Mainly that Sea Foam crap. That stuff is a converters worst nightmare.

Yea, you won't loose torque or hp removing all four. What happens is you move the power band to higher rpms without tuning for it. Thus, losing your low end and some midrange IMO.

 

That was my plan. Just doing 2 high fow cats, and I've heard that there are some that threads all ready for the stock O2 sensors. Any ideas which ones those are? And that kinda pisses me off... I got my truck with a thousand or so miles over the due oil change and had to keep going a lil bit so when I changed the oil, before I did somebody told me to put seafoam in the oil and fuel tank. So I did haha.