The truth about the smell with no cats?
 

I've had conflicting info from members on here. A few told me that their catless exhaust hardly smells at all. Charlie Wheatley said that they all stink without cats. When I fired mine up I noticed a horrible smell so bad I had to leave the immediate area while my truck idled. I'm thinking about getting some magnaflow metallic center spun cats, but that would be a pain in the ass compared to just sticking the OBX ORY in. So can this smell actually go away with a proper tune or what?

I forgot to ask also, if I go with cats do I have to turn my rear o2's back on or can I run it with my current tune just using the front 02s? Thanks

no, no cats will have that pure gas smell that makes my eyes burn....Love that smell on my bike.

i love that smell too. reminds me of the good old days. you get used to the smell and after awhile can't smell it anymore:(

same goes with race gas. i used to be able to pick up the smell from 1/4 mile away. not anymore, you get used to it.

You're a wuss, stop whining...........











In all seriousness, when tuned right they'll stink only a little bit. I would consider it no worse than my riding mower with a 20HP single cylinder. Maybe you're just sensitive? Another member on here didn't like how my truck smelled when he saw it in person, personally IMO it's not that bad. Hell, it's fun to line your exhaust tip to the window of the prius next to you and blow harmful toxins at them. :P

It will never smell like a vehicle with cats on it if it doesn't have them period>>> I like the smell myself..

John

Ran the truck for about two years without cats. Both with long tubes and gutted cats. Never smelled bad.

maybe I'm a wuss, I've never been catless before. If this was a weekend only car I would have no problem with no cats. But since this is my DD I just can't take that smell.

I'm just trying to figure out where the cats can be welded into the OBX Y pipe. I guess the OBX resonators will have to be cut off.

Cut the old ones out and put new ones in. Best bet is to try and off the obx y pipe or send the whole system back, get a refund, then just by headers and have a Y with cats fabbed for you..

John

i don't mind the smell at all. i also noticed that after running a few 5 gallon batches of race gas through it that the sweet smell never really went away :D

I bought my rcsb without cats on it already. Goin from my ecsb with cats to the rc was very noticable to me but nothing i could really care about.
Not to mention it doesn't take long and you get used to it.
I don't mean you don't smell it anymore used to it but rather the doesn't bother you any kinda used to it.That make sense?

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.

pacesetter are 1 3/4" primaries.

Easy really. If it wasn't maxxed out then a cutout would likely have no gains or even lose speed/power.
The fact that once open my trucks runs consistently faster"track proven" it shows that the 5.3l can benefit from even more free flowing exhaust.
Beyond the lt's/3"y-pipe and a catback.
If it didn't need more flow the cutout woudn't help it.

wouldnt that be your catback hurting it, not the headers...?

hence the reason why your cutout helps vs your muffler

If it were your headers being maxed out, the cutout wouldnt give you any gains.

There's no way he's maxxing out the pacesetters. I was told going from a 2.5" to 3" collector might make a difference if I was making 700+ HP

Very well could be. Guess i'm just thinking differant. In the end once the cutout is open it does go faster, so unless i moved up to larger exhaust i can't rule out the system as not holding it back even still.
Maybe it's good enough but unless i tried something bigger and had no gains or loss power then it can't be disproved that the current setup isn't maxxed out.
Oh and now i'm just argueing for the sake of doin it lol.:D:chug:

Just because you were TOLD something doesn't make it true.
Tell the same thing to a guy running a radix. Moving up to a 3" would make a large differance.
700hp isn't as cut and dry as knowing the size exhaust you need.:punch:

dont make me sick low dime on you with the KY! :D


anyways, back on topic, I love the way mine smells with no cats.

You get used to it.

Dear God not that!!!!!! I will leave the thread if i must lol.
Of course you'd have to SIC him on me not sick him on me haha.
I don't mind the no cats on mine. I kinda miss it in the ecsb haha.:chug:

what is done to your extended cab? send it to me in a pm if you want so we dont totally steal this thread

nah, this thread is over. Conclusion = I am a puss. Oh well.

Lol, you just took the first step to recovery.:D

I recently put the 3" spun cats on my truck. I felt a little more low end, I lost most of the rasp from my exhaust and the smell is pretty much gone. starting to miss all of those things, lol.

Showing my age. I remember when they started putting cats on automobiles. Everybody going around saying damn those things stink!

lol!! Full Circle huh? :usa:

MMMM I'll take catless smell over catted (?) smell any day. That's what REAL cars smell like!!! :D

Back in the day, everything I owned was catless...I even pumped leaded fuel for a short while at Hess. Didn't really notice the smell because it's just the way it was. I still love it though...even raw fuel smells good :D

same here man...i usually get complements on how my truck smells :)...except from the g/f:nono:

the smell is lean....when you have headers and no cats, the fumes will burn your eyes, not smell like fuel. Racing fule is awesome smelling but we cant run it because it kills O2's in a heartbeat! So you either have to deal with power loss from the cats or you have to deal with the lean smell at idle. You cant be around any of my cammed vehicles without smelling horrible within a minute. Start em up in the shop and it is really bad. I dont like it but have to deal with it.

Ive read the hi flow magnaflow cats hardly lose any power.