headers with L99 stock exhaust ? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

sub zero · 02-10-2013, 01:20 AM

hi all

what u think if i install new LT headers with stock l99 exhaust would i'll lose the power or the flow or is there any changes if i have aftermarket catback with headers ?

ok , i'll make it simple ...

headers with stock catback or with aftermarket catback ?

i don't care about the sound , just the flow and hp..

BlaqWhole · 02-10-2013, 01:31 AM

Quote:

Originally Posted by sub zero

hi all

what u think if i install new LT headers with stock l99 exhaust would i'll lose the power or the flow or is there any changes if i have aftermarket catback with headers ?

ok , i'll make it simple ...

headers with stock catback or with aftermarket catback ?

i don't care about the sound , just the flow and hp..

Either way, your car will make more power if you upgrade from those stock exhaust manifolds. Some say that an aftermarket exhaust makes no difference in performance on these cars. I and others disagree. But regardless, you will feel a noticeable difference when you upgrade to headers!!

axis · 02-10-2013, 03:12 AM

Quote:

Originally Posted by sub zero

hi all

what u think if i install new LT headers with stock l99 exhaust would i'll lose the power or the flow or is there any changes if i have aftermarket catback with headers ?

ok , i'll make it simple ...

headers with stock catback or with aftermarket catback ?

i don't care about the sound , just the flow and hp..

It's been shown numerous times that aftermarket catbacks/axlebacks add little to nothing in the HP dept, unless you want to count the weight savings. Every reputable vendor on here will tell you the same. What they do add is a different sound. Since you're not concerned with the sound, i'd suggest you just add the headers and see if you like the sound of the stock exhaust. If you don't like it, you can then buy the exhaust of your choice to replace it. No since in spending $$ unless you actually need or want to. Since you have a L99, theres a very nice weight savings in the resonator/H pipe section. Cutting that out and replacing it with a X pipe saves around 18lbs. The X pipe has an affect on the sound of the exhaust as well.

trw427ss · 02-10-2013, 12:13 PM

I have LT headers with stock cat back exhaust and it sounds great! You can see in my sig the difference that LT's make in performance.

1969to2010 · 02-10-2013, 03:01 PM

A buddy of mine has American racing long tubes and stock exhaust he is very happy with it and it sounds great as well

The arh headers with a tune pick up good power I had them before my turbo was very happy

sub zero · 02-10-2013, 03:42 PM

ok guys , what about the big ugly ( resonator ) in the middle of stock exhaust ? is that effect the big flow wich is coming frome new headers or it'll hold some flow ?

1969to2010 · 02-10-2013, 03:46 PM

A good option is to replace it with a cross flow muffler it will flow better , a friend of mine had used a manga flow cross flow

I'd also had the afm tuned out when I did my exhaust ,(I has an x pipe ) the sound made me nuts although my buddy's car with the magnaflo cross flow says he doesnt experience the sound

Pro Stock John · 02-10-2013, 04:02 PM

Has anyone ever cut open the L99 resonator, what does it look like in there?

I'm running Kooks longtubes + cats going into the stock L99 resonator and remaining exhaust. I'm tuned so haven't have AFM in a while. Combo sounds great in upper rpms and at WOT. Would like a little more sound at idle and low throttle.

Mr_Draco · 02-10-2013, 05:05 PM

Quote:

Originally Posted by Pro Stock John

Has anyone ever cut open the L99 resonator, what does it look like in there?

I'm running Kooks longtubes + cats going into the stock L99 resonator and remaining exhaust. I'm tuned so haven't have AFM in a while. Combo sounds great in upper rpms and at WOT. Would like a little more sound at idle and low throttle.

Here's a pic of it.

Bo White · 02-10-2013, 07:28 PM

I have stock GXP exhaust with my long tubes and its 2 1/4"(one reason why the GXP's LS3 is rated at 415hp) and I still picked up a ton of power. Sounds good too...

Fast6.3 · 02-10-2013, 08:00 PM

You shoul add hoflo cats other than the stock manifolds the cats are the biggest choke point

Pro Stock John · 02-10-2013, 10:50 PM

Thanks Draco, always wondered!

trw427ss · 02-10-2013, 11:54 PM

Sound clip of L99 stock exhaust with LT Headers.

VADER SS L99 · 02-11-2013, 01:30 AM

I wish I had kept the stock catback on at the time of my header install and saved the 800 dollars. It has been proven many times that the aftermarket catback adds nothing but sound and weight savings. I might have changed catbacks at the time of my heads/cam install as it might have become a restriction at that power level but on a bolt on car its not going to do anything. Even if it added 5hp are those gains worth the crazy amount of money that cat backs sell for? I say NO.

02-10-2013, 01:20 AM	#1
sub zero Drives: RED@2SS Join Date: Aug 2010 Location: UAE Posts: 1,372	headers with L99 stock exhaust ? hi all what u think if i install new LT headers with stock l99 exhaust would i'll lose the power or the flow or is there any changes if i have aftermarket catback with headers ? ok , i'll make it simple ... headers with stock catback or with aftermarket catback ? i don't care about the sound , just the flow and hp.. __________________

02-10-2013, 12:13 PM	#4
trw427ss Drives: 2013 2SS/RS L99 Join Date: Oct 2012 Location: Denham Springs La. Posts: 811	I have LT headers with stock cat back exhaust and it sounds great! You can see in my sig the difference that LT's make in performance. __________________ 2013 2SS/RS L99/A6 Crystal Red Metallic Tincoat 12.76@108.98mph Bone Stock 12.46@111.19mph with New Era CAI & U/D Pulley 12.12 @ 114.16 after Stainless Power headers and no tune yet on stock P-Zero's! 12.007@ 115.20 With 18" Drag Radials - 11.93 @115.19 Added a PTB 11.76 @116.59 With Yank SS3200 Converter - 11.63 @116.52 After PI and Tuning 11.44 @118.75 New Best 10.72 @127.93 after heads and Cam and Yank SS3600

02-10-2013, 03:01 PM	#5
1969to2010 The Man in Black Drives: 1969 Camaro 2010 Camaro 1SS Join Date: Apr 2009 Location: Long Island NY Posts: 2,016	A buddy of mine has American racing long tubes and stock exhaust he is very happy with it and it sounds great as well The arh headers with a tune pick up good power I had them before my turbo was very happy __________________

02-10-2013, 03:42 PM	#6
sub zero Drives: RED@2SS Join Date: Aug 2010 Location: UAE Posts: 1,372	ok guys , what about the big ugly ( resonator ) in the middle of stock exhaust ? is that effect the big flow wich is coming frome new headers or it'll hold some flow ? __________________

02-10-2013, 03:46 PM	#7
1969to2010 The Man in Black Drives: 1969 Camaro 2010 Camaro 1SS Join Date: Apr 2009 Location: Long Island NY Posts: 2,016	A good option is to replace it with a cross flow muffler it will flow better , a friend of mine had used a manga flow cross flow I'd also had the afm tuned out when I did my exhaust ,(I has an x pipe ) the sound made me nuts although my buddy's car with the magnaflo cross flow says he doesnt experience the sound __________________

02-10-2013, 04:02 PM	#8
Pro Stock John Writer Drives: 2010 SS / 1967 Camaro Join Date: May 2009 Location: Chicago, IL Posts: 7,216	Has anyone ever cut open the L99 resonator, what does it look like in there? I'm running Kooks longtubes + cats going into the stock L99 resonator and remaining exhaust. I'm tuned so haven't have AFM in a while. Combo sounds great in upper rpms and at WOT. Would like a little more sound at idle and low throttle. __________________ PROJECT HEAVY CHEVY Camaro Now: Mods for the Masses Part I \| Part II 13.15@106 1.95 \| 100% Stock 12.37@112 1.85 \| + Kooks Headers/Cats + 20" 555R + CAI + BW TB + UDP + Tune 12.06@113 1.70 \| + CD 3200 + 18" NT05R + RCR Intake + NE OTR + GPI Tune 11.84@115 1.59 \| + 3.91s + Race Star 17x7 Fronts 10.90@125 1.47 \| + GPI VVT Cam + BW Ported Heads + CD 3800

02-10-2013, 08:00 PM	#11
Fast6.3 Drives: 2016 2SS coupe 2015 3LT Stingray Join Date: Aug 2012 Location: El paso texas Posts: 880 View My Garage	You shoul add hoflo cats other than the stock manifolds the cats are the biggest choke point

02-10-2013, 10:50 PM	#12
Pro Stock John Writer Drives: 2010 SS / 1967 Camaro Join Date: May 2009 Location: Chicago, IL Posts: 7,216	Thanks Draco, always wondered! __________________ PROJECT HEAVY CHEVY Camaro Now: Mods for the Masses Part I \| Part II 13.15@106 1.95 \| 100% Stock 12.37@112 1.85 \| + Kooks Headers/Cats + 20" 555R + CAI + BW TB + UDP + Tune 12.06@113 1.70 \| + CD 3200 + 18" NT05R + RCR Intake + NE OTR + GPI Tune 11.84@115 1.59 \| + 3.91s + Race Star 17x7 Fronts 10.90@125 1.47 \| + GPI VVT Cam + BW Ported Heads + CD 3800

02-11-2013, 01:30 AM	#14
VADER SS L99 Drives: 2013 A6 GT 5.0 Join Date: Nov 2009 Location: Edmond, OK Posts: 2,909	I wish I had kept the stock catback on at the time of my header install and saved the 800 dollars. It has been proven many times that the aftermarket catback adds nothing but sound and weight savings. I might have changed catbacks at the time of my heads/cam install as it might have become a restriction at that power level but on a bolt on car its not going to do anything. Even if it added 5hp are those gains worth the crazy amount of money that cat backs sell for? I say NO. __________________ BLK/BLK 1SS/RS Ordered 11-01-2009 Took delivery 12-22-2009. Heads/cam/converter/bolt ons. SOLD Feb 2015 to fund 6th gen LT1 SS with 8L90E.