Which Cat can I remove?

[Keith303]

On my 91 which cat is ok to remove, the one closer to the rear?

 

[mitch]

neither i dont think, there are some post way back i think that talked about that, try to search

 

[spindlecone]

On my 91 which cat is ok to remove, the one closer to the rear?

In Canada you can loose them all, in the U.S. none leagally, you will most likely need an 02 sim if your ex has one downstream

 

[Eric P]

I removed the rear one on my '92 and havent had any problems, BTW, I dont have to worry about smog restrictions. Ive been running it this way for a couple of years now.

 

[Desert Rat]

Hey Eric, did your truck sound any better or have any horsepower gain, cuz I don't have restrictions were I live.

 

[wattsgame]

Some people take and bust all the guts out of them and put them back on the truck so it would apear to still have them.

 

[Keith303]

theres no emmisions where i live anyways, I dont want to remove them cause i need backpressure

 

[holshotracer]

i heard that its a bad idea to gut the cats because it can cause flow problems.

 

[j602]

Either, or both. Doesn't matter, they're both the same, and the only O2 sensors are on the headers, so no code throwing problems. Removing one will boost HP a bit and inscrease sound volume and quality.

 

[huskyfan23]

i heard that its a bad idea to gut the cats because it can cause flow problems.

Yeah man, removing flow restrictions really kills the flow Remove whichever you want. I'd pull them both and replace with a single high-flow.

 

[Eric P]

Gained a little throttle response is all. I dont know if it gained any HP. I ran 2.5 inch pipe back through a turbo muffler. It did make it sound pretty throaty. And it does set off a few car alarms in the parking lots when I rev it a bit.

 

[Desert Rat]

I got a little gains with my set up but I dont know if taking the cats off would make it better.

 

[Keith303]

Hows this sound for a good hp/backpresure friendly set-up

91 4.0

stock headers----->stock cat #1----->eliminate cat #2 with a 2.25" straight pipe leading into a flowmaster 40----->dumped right after muffler with a turndown.

Now i figure this would give awsome sound gains and maybe some HP and still have enough backpresure for the 4.0

 

[j602]

That's basically what I have, except not dumped. It's a solid setup.