5" exhaust?

**Albee** · 06-28-2006, 04:49

I am sure this has been covered, but. I am looking pretty hard at 5" MBRP cat back single exhaust for my 06 LLY. Any known issues with this setup? Or will it plug and play just fine? Thanks to all!

**Kennedy** · 06-28-2006, 09:58

Any exhaust that removes the catalyst will set EGR codes. Some cat back will also do this. We have a Blocker Package that takes care of this.

IMHO a cat back exhaust is for looks only with very mediocre performance gains...

**Mark Craig** · 06-29-2006, 12:20

Albee,

99% of the time you'll be fine, the cat provides enough back pressue to keep the trucks ECM happy and all if well. You'll get approx 85% of the EGT drop and the spool up on the turbo with a cat back as you will with a turbo back, so you'll notice a difference in the truck after the install. HP and TQ are nothign to get excited about but there's a few of them with a cat bcak too! Unless you just "WANT" a 5 inch, the 4 inch will cost you less and get you the same benefits unless you plan to go over 500 RWHP anyway, just an FYI. If you like the look and sound of a 5 incher go for it. If you have any questions call us, we'll be glad to help.

If you want the off road systems that includes the front pipe isn't much more cost wise, but you'll need the "fooler system" that John was takling about as it will most almost always kick a CEL.

Mark @ DPPI

**Albee** · 06-29-2006, 17:55

Mark, you are saying that the 4" will give me the EGT reduction and the turbo spoolup as well as the 5" will? Them are the only two things I am wanting. I do NOT want a loud nasty sounding exhaust system. A little more noise is fine, but I have heard some that are annoying loud. Thanks for your input.

**Mark Craig** · 07-07-2006, 12:06

Albee,

Yep pretty much, until you hit 500+ RWHP you will not see any extra EGT drop or HP gain by going to a 5 inch system.

Mark @ DPPI

**Kennedy** · 07-08-2006, 06:38

People can say what they want about cat back system gains, but think about this. The cat back system seldom sets EGR codes, but the full system does. That tells me that there is quite a difference in flow. It's a lot like toll booths on the freeway. You can run free and fast until everybody has to go single file through the booth. They could all be Ipass for that matter and 60 booths, but the simple idea that you have to line up with a narrow slot will slow things down...

**Hillbilly Jim** · 07-08-2006, 14:26

Great anology! May be five lanes after toll booth but you still have to get through the one lane restriction

**Albee** · 07-08-2006, 22:10

Well I went with the cat back system. I see definite difference in turbo spool up. Nothing astronomical but a definite improvement. I contiplated the turbo back, but just didn't want the hassle of potential problems. Looking at the Airaid intake now. Thanks for all your responses. they are appreciated.

**Inspector** · 07-09-2006, 04:04

Anyone setting codes with an earlier model LB7 (2003) with the cat removed?
Denny

**DmaxMaverick** · 07-09-2006, 10:38

No problem. I've "put out the cat" on several 02, 03, and 04 CA LB7's. Even blocking the EGR is a no-brainer.Removing any restriction in the exhaust (early or late) will offer some benefit, but no appreciable gains will be realized until the "toll booth" is removed, as John says.

Originally Posted by Inspector

Anyone setting codes with an earlier model LB7 (2003) with the cat removed?
Denny

**Driveshaft** · 07-09-2006, 17:07

All sorts of different exhaust systems have been discussed on this board, but best I remember, no one has addressed just simply changing out the stock muffler for a good flow thru and keep the rest of the stock system. Any one have any thoughts on this and would it be enough for keeping down EGT's when pulling loads with say most tuners on stage 1 or even 2? Thanks, in advance.

**SoTxPollock** · 07-13-2006, 10:07

So, Is my 02 with no factory cat better than a 4"cat back as far as flow goes?

**branstew** · 07-20-2006, 09:20

Albee,

If you're looking for an awesome Air Intake, go with Banks' Ram Air System. I just installed on my LLY an love it. 42% better flow area, the intake is enclosed so it keeps the hot, under hood air out of the intake and draws the ambient air in from under the truck as well as the side. Much bigger intake tube and filter box.

**Driveshaft** · 07-23-2006, 16:57

Does no one have an answer to my question on the just changing the muffler for a flowthru and keeping the rest of the exhaust system stock?

**Kennedy** · 07-24-2006, 11:03

I wouldn't waste my time doing it be it straight pipe or muffled.

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