I cant believe it but for the first time in my 20+ years of modifying my vehicles I took a mod off. I'm mad and disappointed. I only had the headers on for a couple of months and they sounded terrible. I had headers on my C5 and another car previously as well. On this truck, the drone was bad, the valve train noise was bad and my truck sounded like a tractor. I am into them for way more than I'm happy to admit but it is just a lesson learned I guess. I thought I did a lot of research so I didn't expect the poor sound.

The good news is 2 fold. I'm getting pretty quick at changing the headers/manifolds on the truck and it has pushed me back to buying a toy. I will be looking at a first gen CTS V on Tuesday evening. Coming from the C5 this is about a perfect car for me as it gets. I sold the vette because I wanted to be able to take the family with me. I feel familiar with the mechanicals of the Cadi and it has 4 seats. Hope my wife doesn't kill me

 

As much as I want to get a set for mine everyone I talk to w/ gmt900 trucks has shitty valvetrain noise w/ them. Have had headers on all my previous vehicles w/ no noise at all but sounds like these trucks are different.

What motor and what muffler set up do you have?

 

Yeah, shitty is about the nicest word I could use to describe all of the sound. I have a 5.3 with a Corsa exhaust. Admittedly the exhaust is not well matched for the headers.

 

sound not sound like a tractor, find a better exhaust to get rid of the drone and etc

corsa is not a good sounding exhaust at part throttle, its a aggressive sound at WOT

 

My 08 4.8 with cam and headers didnt sound like a tractor and i had the cheap ebay headers on mine. I agree with george, a better muffler will make a ton of difference. Id get compliments on how badass it sounded full throttle and at idle.

 

I had drone at anything over 65mph, these made a world of difference on my Borla cat back 140420 kit LINK , but this won't get rid of valvetrain noise.
It's useless now since you removed your exhaust, but maybe it can help others

 

I get sewing machine noise but I dont think it's from my headers, I do get a pretty nasty drone though at 65mph ish

good luck on the CTS build though! I love those cars

 

I've never had a drone, rasp is a different story.
Swap to a stock muffler and cut outs
I am extremely happy with my stock duramax exhaust

 

No drone here with my factory catback (catless, too). My magnaflow exhaust had terrible drone with the factory manifolds and cats.

 

Mine is loud as hell, but the sound is good and deep, not bad/raspy/drone loud. Speed Engineering headers with a single Dynomax muffler and dual out. No Cats.

I have considered adding a resonator or something similar to lower the volume a bit, but actual drivetrain noise doesn't seem to be too much of an issue. - You can hear it, sure....but with a motor swap, cam, head work, etc I kind of expect to hear it.

The only thing I don't like is it can have an incredibly annoying rattling sound at WOT in first gear. I thought at first it may be a leak at one of the connections, but I tried every fix known to the forum short of welding the connections and nothing got rid of it. Honestly, I'm sort of used to it at this point. - may be something as simple as a rattling heat shield....<shrug> The truck runs fine after several months that way so I haven't been overly concerned about it.