To any LLY owners who removed their cat, did you see an improvement in fuel mileage?


Does it throw a code?

Thanks

No and no. I did get a little different exhaust tone which I like. I'll be Juiced this week and see if anything changes.........

I had the Banks system put on 4” all the way back. The service guy at the factory ( Banks) would not by law remove the cat, so I asked how much am I losing he said like 4-5 hp, not enough to worry. I took the “test” pipe home and have hot installed it and probably won’t. I noticed a huge difference in the way the truck breathes by doing the 4” all the way back, and the cat in is no biggie.

___________________________
'04 GMC CC SRW LLY D/A,XM radio TV , Air bags w/controller,Rancho 9000x's ,Rickson Wheels line-x

Max Power,


There is some info in this thread:


http://dieselplace.com/forum/forum_posts.asp?TID=11293&PN=1


who66 is the guy who put the LB7 downpipe on the LLY. Hasn't come back yet with any codes, but it may be too soon to tell.


Dennis

put the mbrp 4" turbo back on about 1000 miles ago. no codes and no big improvement in mileage. a little deeper tone and you can hear more of the turbo whistle.

NO CAT, NO MUFFLER, NO CODES. RUNNING EDGE CHIP AT LEVEL 4. WOT ALL THE TIME, RUNS GOOD SOUND VERY GOOD AT WOT. MORE TURBO NOISE AND LESS LAG.

2000 Miles on full dynomax exhaust, runs a lot better without the cat. No codes. As for the fuel mileage, it may be a bit better 1 mpg or so.

2100 miles on 4" MBRP T-409 SS flange back....


1000 miles on LB7 downpipe to replcae cat....


NO PROBLEMS, NO CODES, SOUNDS GREAT, SPOOLS FASTER!!!


JUST DO IT ALREADY...





BIG

I replaced the cat with the straight pipe about 1K miles ago. I'd previously had the MBRP cat back system on. I have not noticed any fuel mileage increase. When I put the straight pipe on I got the SES light on steady for a bit then it disappeared. It came back on about 400 miles later but disappeared the next time I started it up. I don't know if there are any codes since I don't know how to tell. Does the DIC tell you the code or do you need a code reader? Anyway the sound of the turbo is sweet without the cat and it seems to be a little more responsive when I hit the accelerator.

10,500 miles with turbo back 4" w/Magnaflow muff.. No codes, no mileage, maybe slightly better spool-up, Should be lower EGTs, sounds Good !

Sounds like the LB7 downpipe is the ticket. Now I wonder who might have one whose hands I could take it off of? I'm sure they wouldn't want it cluttering up their garage anymore, and it would make them so happy to provide someone like me with a little bit better truck.


http://www.dieselplace.com/forum/smileys/Ermm.gif


Dennis

me first baimpala http://www.dieselplace.com/forum/smileys/Big Smile.gif

i removed cat replaced with lb7 dynomax downpipe.welded a bung for egt gage. mated to mbrp 304 ss. no codes .1000 miles.sounds great,looks great,spools up quicker.fuel mileage? mybe a little better. to early to tell

me first baimpala http://www.dieselplace.com/forum/smileys/Big Smile.gif





But, I NEEED it!http://www.dieselplace.com/forum/smileys/Big Smile.gif


Race you for it! Crap, you'd win that one already, too.

Downpipes and full exhaust for everyone!
That's a good idea to weld on a bung before installing the pipe.. Lots easier...

Forgive me for posting here, since I have an LB7, but I just removed the cat from my truck tonight. (A big thank you to deadeye for the front-pipe. You da man!) If you look through the four bolt flange into the cat, there's a metal screen at the back of the cat that has to be a major restriction. It reminded me of the bug screen thread, where some people reported increased trans & coolant temps due to the air-flow restriction after installing a screen in front of their radiators.

The truck does sound better now. Has a more "open" or "throaty" tone to it. And it smells like a diesel now.http://www.dieselplace.com/forum/smileys/Thumbs Up.gif I'll probably put about 750 miles on it in the next two days, so it'll be interesting to see if it affects my fuel mileage any.

Dynomax pipe #54194, $130 from Summit Racing, 2k miles, direct bolt on, no codes, increased noise level inside and out, particularly at ~1600 rpms, small mileage increase of maybe .5mpg, smells like a diesel now.

Look here: http://dieselplace.com/forum/forum_posts.asp?TID=10364&KW=dynomax+Edited by: RaceHemi

1000 miles on MBRP turbo back. No codes, same mileage, slight performance imporvement, slightly lower EGT.

i put the full mbrp 4" on last night... and said bye bye to the cat, about 50 miles on it. no codes yet, like racehemi said at 55mph and 1600-1700 its a little loud in the cab, it feels quicker (no lag) at about 55 when you roll into the pedal

Over 8,000 miles since the Kitty "Somehow" got lost.


Never had a code set.


I did it when it had about 25 miles on it so I can't compare any before and after. The new ATS muffler keeps things plenty quiet with no drone.





NOW IF WE CAN JUST FIGURE OUT HOW TO DEACTIVATE THE EGR!!!!http://www.dieselplace.com/forum/smileys/Evil Smile.gif

Anybody who removed their cat and is interested in selling it please PM me. Need one to build a special cat. thanks gardnerteam@bendcable.com

Installed the MBRP about a three weeks ago. Got alot more responsive. Got the SES light two days later. Light went out three days after that. Put the Edge on 9 days ago had the codes erased. Three days ago the code came back, probably the low pressure EGR signal again. Probably gonna put the kitty back on to shut the light OFF!


BTW anybody know what code 1093 is?


Thanks


Rich.

No codes, 5000mi using the Dynomax pipe. Mileage? Can't tell. Doubt if it was affected either way.