[Mark20242SS]

Was doing a little research on exhausts last night, watched a few videos.
is it true you can not easily put on a cat back exhaust with an automatic SS?
something about the V4 mode the automatic goes into messes with the sound?
so i checked out axle backs and the street stainless steel MBRP looked like the best deal. anyone have that and like it? does doing the axle back get rid of the necked down part of the stock exhaust? why did chevy do that? for clearance?
you lose your valve function when installing the axle back? i leave mine in track all the time anyways but nice to have the option i guess. thanks!

[arpad_m]

Many aftermarket exhausts, including MBRP, exhibit audible drone between 1.5k and 2.5k rpm, which can be an unpleasant surprise. More expensive ones like Borla, Corsa or AWE are drone-free.

Tune out AFM (or use a Range device) and you won't have to worry about AFM valves messing up the sound. Catback exhausts are also made specifically for auto trans Camaros.

The crushed exhaust pipe section is there because the convertible has a cross brace in those locations requiring extra clearance, and GM reused the same exhaust components between the coupe and the convertible.

Afermarket axlebacks are available both for NPP and non-NPP cars, naturally those that also contain NPP valves are a bit more expensive. Certain vendors don't offer NPP (valved) variants, either because there isn't enough of a market to justify the extra R&D and cost, or they claim their system is so good you don't need the valves, just 4 exhaust tips.

[sscentex]

Had the NPP. Went to a black widow with vibrant resonator setup without the valves and it drones like crazy at exactly 2k rpms. Got a Borla ATAK axle back delivering Thursday with no valves that I hope fixes it.

I could buy an add on kit for the borla to keep the valves but would rather not.

[Mark20242SS]

thanks for the info! yeah drone does not sound like a good deal.
think i will hold off on those for now and keep my npp stock one for now.
it is nice and loud at start up but quiet driving it unless you get on it.
the npp muffler sure is a big unit though and is it true the ridges in it are for aero ?
& i wish chevy would have used different exhaust for the coupes, that crushed part bugs me lol
they claim it doesnt affect flow much though?

[beowulf556]

Originally Posted by Mark20242SS

thanks for the info! yeah drone does not sound like a good deal.
think i will hold off on those for now and keep my npp stock one for now.
it is nice and loud at start up but quiet driving it unless you get on it.
the npp muffler sure is a big unit though and is it true the ridges in it are for aero ?
& i wish chevy would have used different exhaust for the coupes, that crushed part bugs me lol
they claim it doesnt affect flow much though?

Another option for you is to do a secondary cat delete if you want a little more volume. You really only notice the sound difference when you gun it though.

[arpad_m]

Originally Posted by Mark20242SS

thanks for the info! yeah drone does not sound like a good deal.
think i will hold off on those for now and keep my npp stock one for now.
it is nice and loud at start up but quiet driving it unless you get on it.
the npp muffler sure is a big unit though and is it true the ridges in it are for aero ?
& i wish chevy would have used different exhaust for the coupes, that crushed part bugs me lol
they claim it doesnt affect flow much though?

You can lock your exhaust sound setting to Track in the infotainment, that way it'll only quiet down on the highway. Alternatively, you can pull fuse 51, which will keep the valves open 100% of the time. And if this still isn't enough, fold down the rear seatback for extra volume These workarounds are all free.

The entire NPP muffler itself is an aero piece, aftermarket exhausts typically create a giant cavity there that causes the rear diffuser to act as a small parachute at higher speeds, the solution to which is this belly pan.

As you suspected, the crushed sections have proven zero effect on power output all the way up to 1000 hp, possibly even higher, they just look butt ugly

[WhiteMale]

I think all of the MBRPs have the noise cancelling hemholtz(?) resonator and thus do not drone though I'd need to see pictures to be for certain. I had the axle back with that resonator and it def did not drone at all.

[Mark20242SS]

Originally Posted by arpad_m

You can lock your exhaust sound setting to Track in the infotainment, that way it'll only quiet down on the highway. Alternatively, you can pull fuse 51, which will keep the valves open 100% of the time. And if this still isn't enough, fold down the rear seatback for extra volume These workarounds are all free.

The entire NPP muffler itself is an aero piece, aftermarket exhausts typically create a giant cavity there that causes the rear diffuser to act as a small parachute at higher speeds, the solution to which is this belly pan.

As you suspected, the crushed sections have proven zero effect on power output all the way up to 1000 hp, possibly even higher, they just look butt ugly

yeah i have mine set to track all the time. it is loud enough for me lol.
i did not think of when taking the npp off that you would mess up the aero. yeah the air would catch the diffuser, interesting. yeah saw a racerx video the other night where he replaced his LT1 exhaust and he could not believe the crushed parts would not affect it. most of those aftermarket exhausts are quite expensive also. and it is nice to keep the valve options that come with the npp. thanks will look at that belly pan too.