6.6L L8T Gas Exhaust Options - MBRP, Borla...

[Steph 6.6 HD gas]

Installed an MBRP catback couple months back with no regrets. Sounds bad ass. Nice low tone. Sound like a big block engine.

[Sierra Jon]

These are 3.5" piping right? I'm shopping for a muffler now and will report back. I don't want anything too loud as I will be towing a TT.

Had a Borla ProXS #40359 (5.3L) and a Magnaflow #12909 (6.2L). Both were great, deep sound with absolutely zero drone.

[CT Chevy Connoisseur]

Pulling my hair out waiting for the Borla Sport version to come out.  It has had the "coming soon" moniker for over 6 months.  I've contacted sales and they said "soon" is the best they can say.  They said "soon" both two months ago and six months ago when I asked for more precise timeline. 

 

I think I may just go with the MBRP option since they refuse to give a timeline.

[Steph 6.6 HD gas]

10 hours ago, Sierra Jon said:

These are 3.5" piping right? I'm shopping for a muffler now and will report back. I don't want anything too loud as I will be towing a TT.

Had a Borla ProXS #40359 (5.3L) and a Magnaflow #12909 (6.2L). Both were great, deep sound with absolutely zero drone.

Yes 3.5. No drone. And i also haul a Cargo and TT. I also wasn’t looking looking for loud and it turned out just perfect. And quality of material top notch. 

[Steph 6.6 HD gas]

2 hours ago, CT Chevy Connoisseur said:

Pulling my hair out waiting for the Borla Sport version to come out.  It has had the "coming soon" moniker for over 6 months.  I've contacted sales and they said "soon" is the best they can say.  They said "soon" both two months ago and six months ago when I asked for more precise timeline. 

 

I think I may just go with the MBRP option since they refuse to give a timeline.

Waited 5 to 6 weeks for mine but well worth the wait.  Covid slowed everything down for everything. 

[Sierra Jon]

Not sure why guys don’t just go to an exhaust shop and get them to just put in a muffler and maybe tune up the tail pipe. Cheaper and just as good. The stock exhaust is already 3.5” and they last longer than even T306 in my experience. 
 
I bought a magnaflow, had it installed and also had them install a 60 degree bend behind the last hanger and add a tip so it exited out the side. $450 CDN sounds and works great. 

What model Magnaflow did you go with? Its offset/offset 3.5" right? Do you tow with your truck? I don't want any drone but would love a little more sound.

[L8T]

18 minutes ago, Sierra Jon said:

On 3/17/2021 at 9:40 AM, L8T said:

Not sure why guys don’t just go to an exhaust shop and get them to just put in a muffler and maybe tune up the tail pipe. Cheaper and just as good. The stock exhaust is already 3.5” and they last longer than even T306 in my experience. 
 
I bought a magnaflow, had it installed and also had them install a 60 degree bend behind the last hanger and add a tip so it exited out the side. $450 CDN sounds and works great. 

What model Magnaflow did you go with? Its offset/offset 3.5" right? Do you tow with your truck? I don't want any drone but would love a little more sound.

Magnaflow 12909. 3.5” mufflers that fit are tough to find. 
 

I had to add about 5” to the section of pipe where it drops down In front of the diff to line up but it worked out good. Also cut it off behind the last hanger and installed a 60 degree piece to angle the exhaust out the side. 
 

Drone isn’t bad and yes I do tow. It sounds like a truck now IMO. If one didn’t like it they could put a twister in it also to quiet it down a touch but I don’t feel it’s necessary. 

[Sierra Jon]

Magnaflow 12909. 3.5” mufflers that fit are tough to find. 
 
I had to add about 5” to the section of pipe where it drops down In front of the diff to line up but it worked out good. Also cut it off behind the last hanger and installed a 60 degree piece to angle the exhaust out the side. 
 
Drone isn’t bad and yes I do tow. It sounds like a truck now IMO. If one didn’t like it they could put a twister in it also to quiet it down a touch but I don’t feel it’s necessary. 

Ok thank you! I had the 12909 on my 6.2 and it sounded amazing but I'm afraid it will be a lot louder on the 6.6.

[Sierra Jon]

Installed the magnaflow 12909 and it sounds fantastic. Not super loud but sounds great and has a super deep, low tone. It's in the cab a little at 1500 rpm but it's hardly a drone. Like mentioned above, it sounds like a truck!

 

I posted videos on my Instagram but make sure you use headphones to hear the difference. 

 

Videos are here: https://www.instagram.com/sierra_jon_bongo?r=nametag

 

Cheers!

[CT Chevy Connoisseur]

Went with MBRP cat back - sounds good, probably not quite as loud as I would prefer but options are still a little limited as I will absolutely not put an exhaust that is not T304 Stainless on my truck, only doing this once.  So options were Borla Chevy factory model (still no Borla Sport out yet) or MBRP.  Magnaflow is not an option for the reason stated.

[Andrew Benner]

Anyone go with gibson exhaust? Would like to hear it before I buy.

[shakenfake]

Look it up on youtube. Some of them actually sound pretty damn good

[Grjfer]

Wonder how an electric exhaust cut out would sound? 

[shakenfake]

Just as if it was straight piped. Unbolt your muffler and you'd know haha

[Jello2]

Go with stainless works.  Headers and full exhaust all stainless and everything is high flow. Sounds badass. The worst part is you have to wait a month because they make as they are ordered.