[White1SS]

Is a Green Filter worth anything on a stock SS ?


I'm installing an axle-back to replace my factory dual tip non NPP exhaust, also cutting out and replacing the crushed factory piping near the differential. I was hoping with an axle-back, crush pipe delete, and green filter, I could gain 10-15 hp...am I too hopeful ?

[Megahurtz]

about 3 HP

[NYTMARE23]

Yes. unfortunately I would say 10-15hp by only doing that is too hopeful.. There has already been proof the crushed section of the piping dies NOT hinder performance of the exhaust system. It's GM's way to get clearance. Its just as wide(crushed) as it is around(if you were to "round" that flat section out). Alot of GM vehicles have it(my 2020 Silverado has it as well). Just putting a filter in, will give it a BIT more airflow but not enough of a difference to gain noticeable hp. If you're wanting a noticeable hp gain, you'll need more "significant" mods like headers with cat or axle-back exhaust, a tune, E-85 conversion, bigger throttle body, and a CAI. Those are just SOME things, but there are more. For example, on my ZL1 all I've done "mod" wise is: K&N Cold Air Intake and a Flowmaster American Thunder Axle-Back exhaust with NPP and I left the crushed section alone since it does nothing if I remove it. All I've gotten from those mods is some more supercharger whine and the car is a bit louder with the exhaust on it...DEFINITELY no noticeable hp gains. Of course though, it's YOUR car so feel free to do what YOU want, and ENJOY it!!

[White1SS]

Thanks for the response guys !


I think I read somewhere that NPP adds 5-6hp over non NPP, surely a better flowing axle-back should be worth at least that ?



I know they say the crush pipe doesn't negatively effect things until you reach high HP numbers, but in my mind, even if the "oval" crush section can flow the same volume as the round pipe, there has to be a pressure change there, I would think there has to be something gained by keeping everything round all the way out. 2-4hp ?



If the exhaust is flowing better, I would think a better breathing Green Filter would also aid in flow. 1-2hp ?


I don't want to do anything like headers, E85, CAI, tune, etc until my warranty expires. I was hoping an axle-back, Green Filter, and crush delete would give me maybe 10 hp to tide me over until then. Really I'm just wanting to sound better, and have just a little extra power to stay ahead of the Camaro's contemporary rivals...392/Scat Packs and 5.0 GT's.

[Joshinator99]

Originally Posted by White1SS

Thanks for the response guys !


I think I read somewhere that NPP adds 5-6hp over non NPP, surely a better flowing axle-back should be worth at least that ?



I know they say the crush pipe doesn't negatively effect things until you reach high HP numbers, but in my mind, even if the "oval" crush section can flow the same volume as the round pipe, there has to be a pressure change there, I would think there has to be something gained by keeping everything round all the way out. 2-4hp ?



If the exhaust is flowing better, I would think a better breathing Green Filter would also aid in flow. 1-2hp ?


I don't want to do anything like headers, E85, CAI, tune, etc until my warranty expires. I was hoping an axle-back, Green Filter, and crush delete would give me maybe 10 hp to tide me over until then. Really I'm just wanting to sound better, and have just a little extra power to stay ahead of the Camaro's contemporary rivals...392/Scat Packs and 5.0 GT's.

Negative. Worth virtually nothing. Listen to Megahurtz, he know what he’s talking about.

[CalgaryZL1]

It can’t hurt other that the wallet. You would be the first on this site to do that.

[White1SS]

I have to do an axle-back anyway, the stock exhaust without NPP is boringly quiet. Replacing the crush section at the same time is only another $90 or so, and a green filter, hey why not ...lol.


GM apparently stated the NPP is worth 5-6hp, at least on a Corvette anyway. I have to imagine a good axle-back is worth that as well when replacing a non NPP exhaust.


https://www.camaro6.com/forums/showthread.php?t=447484

[speedyink1]

For the record, GM never stated NPP would make a difference in horsepower for the Camaro. It was advertised as a sound enhancement feature only.

[Evergreen6]

Green Filter?

https://greenfilter.com

Looks like a K&N ripoff, except, green in color....

[Junction65]

Originally Posted by Evergreen6

Green Filter?

https://greenfilter.com

Looks like a K&N ripoff, except, green in color....

K&N vs. Green Filter

[Junction65]

Originally Posted by White1SS

but in my mind

Your mods will produce more sound and thats it. Just because thats not what you want to hear and won't accept it doesn't mean you shouldn't spend the money to do it. Your money, your car so have at it.

[White1SS]

Originally Posted by speedyink1

For the record, GM never stated NPP would make a difference in horsepower for the Camaro. It was advertised as a sound enhancement feature only.

Yes, they apparently stated it for the Corvette. Perhaps a bit of hype for the Vette, or maybe shade for the Camaro ? GM always treated the Camaro as a second class runner-up to the Vette, almost like a nuisance they couldn't wait to get rid of.



I can't image there isn't some degree of HP difference between what is nearly an open exhaust, (NPP) , and a more restricted/baffled exhaust, (Non NPP), be it on a Corvette, or Ford Fiesta.

[White1SS]

Not the most scientific test, but maybe a Green Filter could ever so slightly help with breathing.

[JT6Speed]

Originally Posted by speedyink1

For the record, GM never stated NPP would make a difference in horsepower for the Camaro. It was advertised as a sound enhancement feature only.

True, but it makes you wonder why that would be. Perhaps they didn't want a Camaro with NPP (theoretically 460 hp) to be equivalent to the non-active exhaust Corvette's? But for that matter they could have just done 450 hp for non-NPP Camaro's and then 455 hp for those with NPP.

Regardless, the sound difference and quad tips were worth it enough for me.