Yeah it makes sense. It's too much for me on a daily driver basis. I'm looking into the Magnaflow cats. Maybe I'll see if they can weld my stock cats in. Plus I read on LS1tech that the magnaflow cats flow so well there is essentially no loss in power and it gets rid of the rasp. When I did drive around with the OBX y pipe I noticed it made my 22" magnaflow sound so much better and smoother than with the stock exhaust.

Can anyone tell me if I run cats if I need to have my rear 02s on or will it be okay with just front 02s?

 

You can turn off the rear o2's regardless of having cats or not.
You can't leave an empty hole in the cat of course but turning em off is not a problem.
I have cats on my ecsb but the rears are turned off.

 

I was just asking because I already have my PCM set up for LTs and the rear o2's off. So it's one less thing I need to worry about if I can keep it like that if I add cats.

 

I understand. You will be just fine, like i said i have high flow cats on my ecsb and the rears are turned off. Been this way for 3plus years no problems.

 

I'm anxious to get the headers back on dammit. Just to point out, I run all the time now with the cutout open because the power loss is so signicant when I cap it and run through my magnaflow muffler (otherwise all stock exhaust). Parish demonstrated a 15rwhp gain on a bone stock LQ4 with a cutout over the stock exhaust. When I went around the block with the headers and my cutout closed it felt better than with the cutout open on the stock exhaust. So I know I gained at least 15rwhp. Throttle reponse way better, low end better, just felt like the engine revved faster too.

 

I've got no HP numbers to back me up but i do have track times. On my bolt on 5.3l i gained a tenth and 1 mph with the cutout open and even 60ft better than closed.
So for me at least the cutout does/did help every single run.

 

I think the stock 4.8/5.3 exhaust is complete garbage and is really choking up my 6.0. This is why GM put dual pipes on the 6.0 equipped trucks.

 

If my bolt on 5.3l can max out pacesetter lt's with the 3" y-pipe then i'm sure a 6.0 can do it even sooner in the powerband.
Stock exhaust will of course be crap if a single 3 isn't big enough.

 

The OBX has a 2.5" collector and 2.5" pipes. I think that actually helps low end. And my low end needs all the help it can get with 3.42 gears and 31.5" tires

 

how do you know your bolt on 5.3 is maxing out your long tubes and 3" pipe... I find that pretty unlikely, seeing that the pacesetters are the bigger off the 2 sizes of piping, 1 7/8ths i beleive.