GMCtrk

iTrader: (27)

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?

TouchOfEvil04

iTrader: (13)

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.

GMCtrk

iTrader: (27)

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.

TouchOfEvil04

iTrader: (13)

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.

GMCtrk

iTrader: (27)

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.

TouchOfEvil04

iTrader: (13)

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.

GMCtrk

iTrader: (27)

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.

TouchOfEvil04

iTrader: (13)

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.

GMCtrk

iTrader: (27)

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

00ChevyScott

iTrader: (10)

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.