I want thorley tri-y headers for my 2011 5.3 with stock catback, I've decided for sure that I want those headers. But, the 310y-1-c come with a cat-less ORY and the 310y-49-c come with a flange that you weld on just upstream on the cats.

So the question is really, do I keep the cats or go with the ORY?

Benefits of the ORY, it's a true bolt-on I can install myself, but if I need warranty work then I'll probably have to put back on stock parts? Benefits of stock Y, maybe GM won't scream about no Cats if I ever need service, supposedly better exhaust smell, but I'll have to pay for the install.

Is there a performance difference? Both are the same price from BB.

 

You on the Missouri side of KC or the Kansas side? If you are titled in Missouri, you probably better keep the cats. If you're worried about warranty, keep the cats.

 

i would go catless since the thorly tri ys are only 1 5/8" diameter. i was looking at those but i chose the kooks with catted y.

 

On KS side and don't think inspections are a problem. I figure if I have a drive train warranty issue I'll have to decide to put back in stock parts before I take it in. Although I can see were that would be a huge pain and not very probable.

Thorley is priced right and I like the 1-5/8 idea for a DD.

I wonder what GM would think if I put the stock cats in the thorley Y?
Also, is smell really a problem with no cats?

 

I have the exact same setup with the cats on. I wouldn't remove the cats, you don't really gain much and the drone on these will be so annoying. So for me it's a definite no no. Plus you need the back pressure for good torque.

 

Did you put the factory cats in the thorley Y or use other cats or fab up your own Y setup? Thanks for the input too, it helps a lot. This is why I was thinking the -49 model, to keep factory Y setup.

 

Stock cats.

 

Got any pics of that?

 

Unfortunately not. Sorry.