straight pipe

[swamper74]

I have an 06 duramax I put a pipe in place of the muffler amd still sounds the same not loud at all what should my next step be? I just would like it to be louder should I put a muffler on? Thanks for your time and answers.

[CarolinaHD]

take the cat off

[TexMax]

Mmmmmhm

[TexMax]

YES! I finally identified this internet page! I have been seeking just for this write-up for so extended!!

The ****?


Am i about to receive a large sum of money from a long lost uncle?

[farmboy1466]

I'm not sure how the duramaxes are set up, but a buddy of mine had to change his down pipe as well on his 08 cummins to make it louder. It had some stupid filter in it.

[Heavytruck]

I just installed a 4 inch kit, not loud at all, That's withiut a cat or muffler.

[squeaky3]

i have 4" straight pipe, no cat and no muffler and mines pretty loud


http://www.youtube.com/watch?v=d6FZ26TxvjM&list=UUSa6GnK1n3x6iUM2WHQMDhg&index=2&feature=plcp

[Jmac72]

I just installed a 4 inch kit, not loud at all, That's withiut a cat or muffler.

The variable vane turbo does a very good job of muffling the sound.The older LB7's are noticeably louder.
With efilive you can change the vane position at idle and get a little more rumble.But when you stand on it,it quiets back down a bit.

[DarkCharisma]

Quiet is good. :D

[oldred95]

Part of the reason why the old LB7s are so much louder under a load is the waste gate popping open. Stock they are regulated to about 18 psi. On my dads 2002 LB7 with a tow tune I can clearly hear the waste gate pop open around 2200 rpms with moderate to heavy throttle. The PPE boost valve is basically a non adjustable boost controller that lets it boost up to 28-30 psi.

On the LLY and newer engines there is no waste gate and all the exhaust is passing through the turbo and out the vanes. I would imagine the turbo is keeping the exhaust pulses contained and going in the same direction and keeping the sound down similar to how a muffler does it. They can still roar under the right engine load but they are still not as loud as the LB7.

[DarkCharisma]

They can still roar under the right engine load but they are still not as loud as the LB7.

WOT is the only time I can really get mine to roar at me.

[Heavytruck]

I really wan't going for super loud anyways, just better flow, and lower exhaust temps

[VenomousGT]

My lb7 is pretty tame with my full banks setup... Been thinking about removing the muffler on mine too.. I hear the lb7 is louder straight piped because of the lack of cat and the lack of the veined turbo


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[DarkCharisma]

My lb7 is pretty tame with my full banks setup... Been thinking about removing the muffler on mine too.. I hear the lb7 is louder straight piped because of the lack of cat and the lack of the veined turbo


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You would be correct. Significantly louder, actually.

[bclax1408]

Look into getting a bigger exhaust. i found a 4 inch straight pipe kit for my 01 cummins for $350 with a 4 to 6 inch exhaust tip. That was from the turbo back, downpipe and all. look at farmboydiesel.com to see what you can find for your duramax. and remember, bigger is always better right? :cool:

[Mark13]

Look into getting a bigger exhaust. my 01 cummins, and remember, bigger is always better right? :cool:

No.

[Jmac72]

There really is not much benefit to go bigger than 4".Unless you are running twins,or a big single.Some guys say the 5" sounds better,but I can't tell much difference.

[CarolinaHD]

5" is definitely deeper, but not worth the money if you already have the 4"

[ATH0201]

If you replace the stock exhaust system on a 06 LBZ with a 5" straight Farm Boys Diesel kit and have no muffler or CAT, are you going to have problems passing inspections without knowing an Inspector personally? I am in NC.

[CarolinaHD]

No you'll be fine, all pre emission diesels (07+ require dpf) are subject to an annual safety inspection but no emssions testing.

For the record, knowing an inspector is worthless know a days. The dmv has been cracking down hard recently and most normal people don't want to risk the 4 figure fine just to pass some dude's truck. I have heard of a few stories of someone going to get inspected, failed, then going to another station and pass, only to have someone from the dmv show up to their house and inspect it themselves. Resulting in fines for both parties involved.

Just a fyi for those of you out in internet land.

[squeaky3]

Im glad i dont have any inspections on mine....yet. with regular truck plates there is no safety inspection...when i jump up to a bigger weight class plate so i can pull more legally, then i will have a safety inspection...but still no emissions testing here