Darrel from Meraux

You guys are probably going to kill me for having to go over this again but im still unsure. Im about to install my lpp longtubes on my 08 sierra. First off I want to run cats, I dont want rasp or smell, but I dont have to worry about any kind of emissions tests in LA. It seems like my two options are to weld in 2 3'' magnaflow spun cats into my y pipe OR weld a single cat into the exhaust system just behind the y pipe and tune out the rear 2 o2 sensors. What are you guys opinions on both the 1 or 2 cat system. Im sure the 1 cat system would be easier and cheaper but would I gain anyting by running the 2?

grey matter 04

iTrader: (9)

man run it with no cats!
A bigger muffler will kill the rasp
But if you absolutely stuck on running cats i would run one cat
No need to choke it down with 2!

Darrel from Meraux

I'v been told that with no cats my low end will go to crap. Anyone have some real world experience on low end with no cats?

grey matter 04

iTrader: (9)

I doubt you notice much loss of lowend if any
I dont recall any when i cut off my cats with stock y pipe

Darrel from Meraux

Ah, If I do any im hearing 2 will flow better aqnd last longer. Thanks for the help.

Nuclear Endless

iTrader: (4)

I dont know why you would go with 2... stock only has two for emissions purposes and because its convenient with the huge stock y pipe.

I would go with one cat further down the exhaust.
Also means if you ever sell the longtubes in the future the y pipe wont have been ruined

kr1s

I doubt you will feel the low end loss lol
I know what you mean i want to run cats too.... so i just said fk it and i'm running my stock exhaust for as long as i can

Darrel from Meraux

Thinking about doing the header install tomorrow or monday and running the ory for a few weeks to see if I really want to add cats. I know running longtubes usually make your truck run rich. Is there any chance that instead of rich it could lean my truck out? Asking because I wont be able to take my truck out of service for a retune for a few weeks. Wondering if its safe to run them with no tune for a few weeks.

FrankyRST

iTrader: (7)

On my 09 rcsb I did pacesetters with ory, left a space for the cutout, put in the third cat/resonator that the 09+ trucks come with, and then a 24" magnaflow. I was suprised at how quite it is and I could hardly smell the exhaust, except for that new longtubes smell that lasts a couple of days. If I were you I would just get a big muffler, and if you still dont like the loud sound or smell, I would add a cat or resonator before the muffler.

snorris

You wont loose any low end torque with no cats. I have headers with an ory on both of them. I use my truck to pull trailers frequently and have no issues.