LBZ onwers thinking of removing the cat..... [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: LBZ onwers thinking of removing the cat.....


Tom S.
09-13-2007, 05:06 PM
A word to the wise! I replaced my stock exhaust a year and a half ago with the MBRP cool duals in 304 stainless steel. I recently decided to remove the cat in an attempt to lower EGT more when towing.

I have read posts here that stated it took 1/2 hour to an hour to do the job. I wish those guys had been here to help! It took me 3 hours to do the switch. The first obstacle was getting the exhaust separated from the cat. The cool duals came with a reducer that goes between the cat and the pipe going to the muffler. Getting it loose was no problem, but trying to get enough 'play' in the system to separate them was an issue. Dropping the down pipe from the header wasn't any help because the cat was prevented from moving forward by the hanger bracket, and I struggled trying to get the exhaust to move back far enough to separate the two. After a lot of frustration that even included removing the cat hanger bracket from the trans, I got the two apart. It took about 15 minutes of twisting/turning, plus raising up the truck slightly to get the cat out from under the truck.

Then came problem #2. I couldn't get the reducer off the cool duals pipe. Although I wanted to keep all the parts in case I want to switch back, I could not get it to separate from the exhaust. By this time I said *****it and cut the damn thing off. Don't get me wrong - I tried to remove it in all manner of ways, including penetrating lube and judicious use of a hammer, but it just wasn't budging.

Ok, I'm ready to put the new pipe in - how hard can that be? Well putting it in isn't hard at all except for one little thing - the hanger. You see the hanger faces the front of the truck. That means if you slide the pipe in from the back in order to get the bracker in the hanger, you can't slide the pipe far enough forward to slide it back over the exhaust. If you slide the pipe in from the front of the truck, getting it on the exhaust in no problem, but now you can't slide it in the hanger bracket. I had already put the hanger bracket back on the trans - so off it came again. It still wasn't easy. The hanger on the pipe didn't line up where it should have. Since the front of the pipe has a flange, you are very limited on how much adjustment you have to get the frigging hanger lined up. Anyway, determination, a pry bar and a lot of words my mother never taught me paid off, and I finally got it together.

So what is the lesson? If you are even remotely thinking of removing your cat, and are in the process of ordering a new exhaust system - it will be far easier to do the cat now instead of waiting.

And if you already have your exhaust on and want to delete the cat, get one of those guys who can do it in a half hour!

AGGAR
09-13-2007, 05:49 PM
Sounds like it was a big PITA! How's yoj egt's now?

Ryan

Tom S.
09-13-2007, 06:30 PM
Sounds like it was a big PITA! How's yoj egt's now?

Ryan

I haven't tried towing yet - our trailer is in the shop getting stuff fixed. I have read that you can drop the temps between 75 and 100+ degrees.

PC HOTROD
09-13-2007, 07:16 PM
What's the exhaust sound like with the cat removed and did it throw it any codes?

DmaxHawk
09-13-2007, 07:28 PM
Same question^

carcrafter22
09-13-2007, 09:42 PM
WOW I am sorry to hear that i did my cat delete in a hotel parking lot when I was away on buisness with a couple hand tools in about 20 minutes. How do you like the new sound I love mine.

jmac660
09-13-2007, 09:50 PM
Mine has a nice mellow tone until you get into it then is sounds like a jet. No CEL for me.

Tom S.
09-14-2007, 06:04 AM
Like jmac660 says, it sounds fairly throaty until you get on it - then it sounds like a jet. As a side note, it made an improvement in throttle response and I can feel the difference. That surprised me because I didn't think removing the cat would have that big of difference.

No codes yet but it's way too eaerly to tell.

godaddy
09-14-2007, 06:39 AM
There is no since in doing the exhaust on these things and not get rid of the cat! Just get a system that u can but just the cat back on if need be. IMO

LWATSON
09-14-2007, 04:56 PM
Cat back systems do just fine:)

ColbyColorado04
09-14-2007, 05:01 PM
I killed the kitty in about 20-25 min myself and that was including the time to remove the pass side inner fender to make it easier to reach the clamp on the dp. took a lilttle twisting to find the right angle to get it out but it wasnt too much trouble. I have heard some with horrible time getting it out and some like myself that had no real issues.

1lowdiesel
09-14-2007, 05:21 PM
Like jmac660 says, it sounds fairly throaty until you get on it - then it sounds like a jet. As a side note, it made an improvement in throttle response and I can feel the difference. That surprised me because I didn't think removing the cat would have that big of difference.

No codes yet but it's way too eaerly to tell.

thanks for clearing that up. i tell that to people all the time when they ask how it will sound and make a difference and they never believe it.

dirtymax07
09-14-2007, 07:11 PM
Killed the cat and it dropped egt's 100+ . Did take a little longer than planned and also created some new words.:p:

Bobcat2002
09-14-2007, 08:05 PM
Some people are getting the cat killed in the parking lot of Walmart for free. Only problem is you don't get a cat delete pipe. and it is not a pretty job lol

dmax3500
09-14-2007, 11:14 PM
1.does the truck run any better?
2.is there any fuel milage improvements?

Tom S.
09-15-2007, 09:23 AM
1.does the truck run any better?
2.is there any fuel milage improvements?

As I stated, I was surprised that the truck does run better. I'm one of those guys that when someone puts a 'superduper turbo express muffler" on their ride and then claims that it made a huge improvement in HP, rolls my eyes and says "yeah, right". But I do have to say that in my case it did make a substancial improvement. However, I do have to qualify that statement because I am also running the Cool Duals and a programmer, which I am sure both benefited by the change.

As for mileage, it's too soon to tell and typically, I only monitor milage when I'm towing. There are too many variables when driving around town.