Yes it will sound different. That high pitch scream will go away or be lessened by a lot with a round pipe. I hate that scream sound.

 

I hate the scream with a stock downpipe. Any of my LBZ or older trucks that is one of the first things I always did. I cant say how much difference it made on my LML because I did a cheetah at the same time, but the idle is definitely slightly deeper than it was

 

idk how you could hate that sound it sounds amazing

 

It changes sound but trust me it will be a sound you like.

 

My sound really changed when I replaced the down pipe & installed a Fleece 63mm Street turbo. Now I have a "whistle" from 1500-2000 RPM's...

 

Not compared to the growl through a 3in downpipe. The sound of two owls 🤬ing coming out of my tailpipe is so annoying. The throaty growl of a V8 under throttle is so much better. Back in 2017 I bought my third LBZ and immediately put a 5in exhaust on it, then made a trip from west-central Indiana to White Plains Georgia for Diesels in Dark Corners towing my gooseneck and LB7. Going through the mountains, I almost stopped to buy ear plugs because I was on the brink of killing someone because of the sound through a stock downpipe. Never again will I put exhaust on an LLY/LBZ truck without having a downpipe there to put on it at the same time

 

idk man that scream like in the video i sent sounds frickin wicked anyone have a launch video with a aftermarket downpipe??

 

Stock down pipe doesn’t sound horrible as long as you don’t put 5” straight exhaust on it. Especially for towing.

 

I dont get why people dont like the 5” exhaust. They are quieter than a 4” in my opinion. Ive got a 5” no muffler on mine and love it but I’m not towing campers either. Nor do i have a stock turbo.

 

4 inch straight or 5 inch with muffler, in my opinion. Its all about the resonance. Unloaded around town is significantly different than 5 hours loaded

 

Let me break it down, the sound you like...that stupid whoosh at high rpm with stock downpipe is air not flowing out of downpipe like it should, it is the sound of a tad higher egts, and just less performance. Put a aftermarket one and you will get the sound of cooler egts, the true sound of a duramax, and the air esacpign with less restrictions. You do you but trust me 130 for a downpipe is worth it to me.

 

There are different brands of 5" downpipe back exhaust that will sound different. I just told my performance shop to put a good one on. Can't find the paperwork that tells me what it was. The only time I get a resonance drone is pulling long steep hills with the fifth wheel. That I can live with.
My BIL put a cheap 4" and his sounds like a pissed off hair dryer and the drone is bad even when not pulling a trailer.

2007 2500HD Classic 4x4 LBZ

 

im hearing that with a aftermarket down pipe apparently it gets rid of the duramax "scream" witch sounds amazing i have a 2014 lml and i bought a ppe 3" downpipe for it i haven't installed it yet but im wondering if i need to box it up and return it if it gets rid of the amazing scream sound LML duramax boosted launch will it not sound like this anymore??

Something that no one has addressed is the material from which the pipes are made of. I prefer the 304 Stainless Steel, after being in the boating world for over 30 years I can tell you for sure the material from which your pipes are made also effect the type of sound, from what I have experienced it makes the sounds deeper.

 

I have 3 videos for you but can’t figure out how to post them from my iPhone. If anyone knows how let me know and I’ll do it.

 

Easiest way is to upload to YouTube then post here. Or since you're on iPhone share from iCloud.

 

My lly droned the worst when I had the 5" straight pipe dumped right over the rear axle. It was deafening when pulling a heavy load at about 2-2.5k rpm. Might even call it "exhausting". Sorry. Bad dad joke.

I also debated on ear plugs. Seemed like the stereo and the exhaust were always fighting to be in charge.

Got so much better when I switched to a 90 normal exit angle.

Then it became a much more sinister, head turning sound when I put the 10 blade turbo on. Miss that sound... sometimes lol