I read alot about how the sound and look is improved with the addition of a cat back system while leaving the cat convertor in place. Can any one with an LLY comment on the performance increase they experienced such as better highway passing or more off the line jam?


I would like things to run a little cooler for towing but at 600 dollars I would like the performance to improve as well. The idea of a chip is not that appealing to me so exhaust and intake are my options. Thank you for all your replies.


Edited by: AbsoluteGMC

Well, I drove the TTS shop truck with tow-tune and catback on it. Smooth, quiet, and fast. How much of it was the catback? Dunno.

I have a LB7 completely stock tuner wise. I have a K&N FIPK intake with a AFE Proguard 7 Filter and a Magnaflow stainless cat back. I notice some power increase daily driving. I noticed an even bigger difference towing. Egt's dropped while the power increased. And mileage slightly increased. Well worth the money from a performance, sound, and appearance standpoint. Get the magnaflow cat back with the stainless tip welded from the factory. Looks nice.

My CAT back was installed after the Juice because I wanted an EGT drop.


I got an EGT drop from the CAT back, but since it's never been timed or put on rollers, all I've got is seat of the pants. Nothing noticeable performance wise, but then all I wanted was a reduced EGT and it did that. Not as much as a full system according to posts I've seen here.

Uphill climbs seemed easier to me. Seat of the pants was my judgment also.

Do these trucks have a cat because looking at the exhaust piping there does not appear to be one. I removed the muffler and would then remove the cat if indeed there was one.


Ben http://www.dieselplace.com/forum/smileys/Rock On.gif

Mine came without one. Muffler only from the factory.

Do these trucks have a cat because looking at the exhaust piping there does not appear to be one. I removed the muffler and would then remove the cat if indeed there was one.


Ben http://www.dieselplace.com/forum/smileys/Rock On.gif





CATs are on CA emission equipted LB7 trucks sold there, also they were sold in a couple of NE States. All LLY equipted trucks have CATs.

I have the banks exhaust and afe intake and noticed some extra oomph..Not huge by any means,but EGT's dropped and there is some extra off the line power there.worth it IMO

Anything that makes more power is a good thing.http://www.dieselplace.com/forum/smileys/Clap.gif

By removing my muffler will this drop my EGTs or not. I thought it would. What other option should I do so my EGTs would drop?


Ben http://www.dieselplace.com/forum/smileys/Rock On.gif

Egt's will drop but will be loud as h#ll. Just do a catback. Or just do a replacement muffler if on a budget.

The noise is not loud at all. I thought by removing the muffler it would be annoying but actually I would like it louder.http://www.dieselplace.com/forum/smileys/Evil Smile.gif Anyho I do like it and when pulling my 5er it is not loud either. When you tromp on it hard it does rumble some.


Ben http://www.dieselplace.com/forum/smileys/Rock On.gif

But What About the gains in performance?

I know but just curious about engine withstanding all these performance mods and gains. Just wondering!


Ben http://www.dieselplace.com/forum/smileys/Rock On.gif

I think you've gotten about all you are going to get on this question.


Basically the mod you're talking about is not something folks who regularly dyno or race their trucks would do, and nothing else. These two mods are normally done by those folks in conjunction with other mods and usually remove the CAT, so I doubt you'll see any hard numbers. I've not had mine on a dyno, but would like to some day just to see where it's at, however I certainly wouldn't go to the hassle and expense of running it on the rollers before and after a CAT back exhaust change just to see what it was.


IMO the performance gains acheived by those two mods alone, if any, would be so negligible as to be not worth talking about, despite some manufacturers claims to the contrary. If all you want to do is those two, you'll see an EGT drop, a little extra sound and possibly a very slight MPG increase. Maybe some who have done it do feel a "seat of the pants" difference, but I have not and it's a highly un-reliable measurement standard...http://www.dieselplace.com/forum/smileys/Ermm.gif

bsouuteGMC,


You'll get lower EGT's faster spooling turbo and possibly some MGP form exhaust and intake mods. You will get a noticeable "kick in the pants" too.


We have aluminized, T-409 and T-304 stainless single and duals from MBRP and we guarantee all of our pricing to be the best, take a look at this link:


MBRP EXHAUST (http://dieselplace.com/forum/forum_posts.asp?TID=11123&PN=1)


It's from the review section of this site, great info and pics for you to look at.


Mark @ DPPI

Zeeb,


I don't know. If you have an ANSI calibrated pants seat, it can be pretty accurate.http://www.dieselplace.com/forum/smileys/Big Smile.gif I haven't had mine calibrated in a while, but I have had to upgrade my pants to a bigger size. They sound a lot better (much deeper rumble) and look great.


DennisEdited by: baimpala

Dennis,


My point exactly. If you want more sound, there are systems to do that, or systems which don't make a lot more noise which is what I wanted.


But all this talk about performance gains and what it would cost for both the CAT back and new intake really confuses me. For about the same amount of money, you can get JUICED....http://www.dieselplace.com/forum/smileys/Big Smile.gif


And while my pants seat ANSI calibration is not current either, I can tell you the Edge made a h*ll of a lot more difference than the exhaust...http://www.dieselplace.com/forum/smileys/HiHi.gif

Very True, the chip is more power per dollar... however some of us just are not comfotable raising the power levels to that point so we opt for the cooler running exhaust and intake mods. I'm still waiting to see the results of spicer's air filter test and what the difference is between manufacturer claims and reality! I am just pricing out different exhaust systems and have come down to Magnaflow and MBRP. Thanks for all your replies.

Zeeb,


I meant my pants. http://www.dieselplace.com/forum/smileys/Big Smile.gif The exhaust sounds pretty good, too. I don't notice any seat of the pants difference either, but coupled with other mods it may make a little difference (marginal?). I KNOW I'm going to feel a difference with the Juice/Attitude, just waiting for the Fed-Ex guy to show up. . .


Dennis

I'm still waiting to see the results of spicer's air filter test and what the difference is between manufacturer claims and reality!


As am I waiting. I'm not convinced that any of the aftermarket low restriction intake systems will provide the same kind of filtration capability as the OEM paper elements.


If Spicer's tests show otherwise, I'll add an intake system to my sig...http://www.dieselplace.com/forum/smileys/Approve.gif

I'm with Zeeb on that one.


Increase Performance but do no harm!

My CAT back was installed after the Juice because I wanted an EGT drop.


I got an EGT drop from the CAT back, but since it's never been timed or put on rollers, all I've got is seat of the pants. Nothing noticeable performance wise, but then all I wanted was a reduced EGT and it did that. Not as much as a full system according to posts I've seen here.








Zeeb,


How much of an EGT drop did you get with the CAT back? I have the juice w/attitude, stock exhaust and would add the CAT back if the drop is significant like 150-200 degrees F. I don't want to remove my CAt as testing is likely in the not too distant future (Nor Cal).


Steve

Steve,


You won't see that much drop in the EGT's, or at least I didn't. When I first put it on, I got about 125 to maybe 150, it's tough to tell with the way it moves up and down. That was at 70mph on the freeway unloaded and with the first Beta release.


The temp drop seemed to go away with the second Beta release, but ambient temperatures were up and Edge claimed it should be cooler. I've not driven the production release enough to tell yet, but it's the smoothest of all of them.


The stock muffler is a real plug in the system from what I've read, but I can't remember where I saw the test results on mufflers. Some have suggested just replacing the muffler would do as much for cooling, but I didn't want a lot of noise. So based on some recomendations here, I went ahead with the Banks. Nice looking double walled tip and even a polished muffler which nobody is going to see, and it went on really easy.