Replacement cats for good sound

[Sam Harris]

So when I need to do my exhaust, I was planning to go with some "high flow" type replacement cats. I'm in Co, and they do poke around a bit with the smog test, although, are completely clueless, doing silly things, like pulling the manual choke in my old Wagoneer.. ahem, that aside, I'd rather a cat delete, but don't want the hassle of potential smog troubles.

I believe the stock exhaust is 3.5", so could probably get a set of universal cats, but seems like those are garbage, and don't last.

FWIW, I would like a better sound as well, and deleting the cats would help with this, but can I just get shells, to make the cat appear to be there... ?

Recommendations?

'03 Yukon SLT 5.3

 

[01DenaliHiker]

Running just a shell will sound tin like and ruin anything you wanted to accomplish. You can have someone weld pipe through a shell to leave the appearance of the cat, but still maintain the delete sound. That's how I got around it in Texas with my FJC years ago. Empty shells made me sound like an angry Honda Civic in a parking garage.

 

[swathdiver]

So when I need to do my exhaust, I was planning to go with some "high flow" type replacement cats. I'm in Co, and they do poke around a bit with the smog test, although, are completely clueless, doing silly things, like pulling the manual choke in my old Wagoneer.. ahem, that aside, I'd rather a cat delete, but don't want the hassle of potential smog troubles.

I believe the stock exhaust is 3.5", so could probably get a set of universal cats, but seems like those are garbage, and don't last.

FWIW, I would like a better sound as well, and deleting the cats would help with this, but can I just get shells, to make the cat appear to be there... ?

Recommendations?

'03 Yukon SLT 5.3

I posted a video on my youtube channel of my stock exhaust with Magnaflow Y-pipe and cats on start up. Stock exhaust is about 2.75" for the 5.3 motor.

 

[Sam Harris]

I posted a video on my youtube channel of my stock exhaust with Magnaflow Y-pipe and cats on start up. Stock exhaust is about 2.75" for the 5.3 motor.

Sounds good. I suppose it would be pretty close to the same on my ‘03. Stock, magnaflow muffler & y-pipe w/ cats? How long is the muffler? Thanks for sharing.


Sent from my iPhone using Tapatalk

 

[swathdiver]

How long is the muffler?

I dunno, it's still original. Only the Y-pipe with cats was changed.

 

[Sam Harris]

Ok, gotcha. I misunderstood. Thanks much!

 

[iamdub]

So when I need to do my exhaust, I was planning to go with some "high flow" type replacement cats. I'm in Co, and they do poke around a bit with the smog test, although, are completely clueless, doing silly things, like pulling the manual choke in my old Wagoneer.. ahem, that aside, I'd rather a cat delete, but don't want the hassle of potential smog troubles.

I believe the stock exhaust is 3.5", so could probably get a set of universal cats, but seems like those are garbage, and don't last.

FWIW, I would like a better sound as well, and deleting the cats would help with this, but can I just get shells, to make the cat appear to be there... ?

Recommendations?

'03 Yukon SLT 5.3

All cats, OEM and aftermarket, are "high flow" and this term is used primarily as a selling term for cheaper, low-quality cats. If your current cats are fine and you just want more or better sound, change the muffler. If your cats need replacing, your best bet is OEM or whatever aftermarket brand has been found to be a viable replacement. There are so many cheap aftermarket ones that don't have enough catalyst to perform sufficiently and about the only way to weed them out is by word of mouth. Apparently, whatever Magnaflow uses is fine. If you wanna not have to worry about cats, delete them. If you wanna delete them but pass visual inspection, you can have your stock ones hollowed out and a straight pipe slipped all the way through them and welded into place or get the pre-fabbed ones such as >THESE<. With any form of deleting, you'll need a tune to keep the PCM from throwing codes, which will fail an inspection. Deleting the cats (straight pipe or with false cats) and having the PCM tuned is much cheaper than replacing the cats even with cheap aftermarket ones.

 

[Sam Harris]

Thanks for the info! I knew a delete would require a tune, which, gosh... I might need my arm twisted to get an auto-cal...

 

[iamdub]

Thanks for the info! I knew a delete would require a tune, which, gosh... I might need my arm twisted to get an auto-cal...

You can get a much cheaper tune to just turn off a few things and make some small changes. You don't have to get a full-on power tune if it's not in your interest or budget. I had a local speed shop turn off my rear O2 sensors, remove the speed limiter, reduce Torque Management and turn off AFM for $150.