[Z OH 6]

Originally Posted by airtroop01

Clarifying my statement:

I did two events besides street/highway driving:
(1) Car rally that was about 280mi and 5 checkpoints
(2) SCCA autocross event.

Initial observations:
Quieter, really nice sound. Minimal and medium load situations are fine. With the 2650 and a ton of torque, you can get around most cases using only 10-30% of the throttle and the setup was perfectly fine.

Further observations (40% throttle - 100% throttle):
1. Mid throttle, high load situations
I was getting some bucking as the boost went to about 15psi - something I did not experience before and I'm not experiencing it right now as I pulled the muffler out yesterday.
I data logged some of this with the PDR: coming out of a turn 20mph, 1.1g, accelerating to 60mph. Tried in 2nd gear and 3rd gear. More pronounced in 3rd gear and a bit better in 2nd gear.

2. WOT scenarios
- i.e. coming out of a turn (low speed 30mph about 1.15g according to PDR) to about 125mph. Visible jagged edges on longitudinal acceleration throughout RPM band.
- also noticed this on many highway pulls 40/50/60 roll to 120+ speeds. The car would just sit back instead of propelling itself (if that makes sense at all)

Had both myself and some instructors/passengers who came for a ride with me and driven the car note that it felt choked off because the power comes on wanting to go and you can literally feel it in the pedal rolling back on you.

Keep in mind, if you're happy with it... keep running it.
Just trying to share my experience and maybe it will help some of you.
Without the muffler, WOT - the car took off with the pedal mashed to the floorboard while trying to break traction on the freeway.

It's all good, just trying to understand your experience since it doesn't line up with anyone else in this thread. I just find it odd. My car makes 15psi of boost as well, but I've never seen any issues before or after the muffler. Understanding that my car doesn't make as much power as yours, but 700whp should still be WAY over the limit for this muffler if this were just based on the math. Did you ever add headers? I know at one point you were making 800+ WHP through the stock manifolds. The reason I ask is that exhaust is always most restrictive closest to the engine, so the manifolds are the most restrictive, then the cats, then the rest of the exhaust. If you were still running stock manifolds, you were already choking the engine and then the muffler would have just been too much for your car to tolerate. Just spitballing.

[airtroop01]

Originally Posted by Z OH 6

It's all good, just trying to understand your experience since it doesn't line up with anyone else in this thread. I just find it odd. My car makes 15psi of boost as well, but I've never seen any issues before or after the muffler. Understanding that my car doesn't make as much power as yours, but 700whp should still be WAY over the limit for this muffler if this were just based on the math. Did you ever add headers? I know at one point you were making 800+ WHP through the stock manifolds. The reason I ask is that exhaust is always most restrictive closest to the engine, so the manifolds are the most restrictive, then the cats, then the rest of the exhaust. If you were still running stock manifolds, you were already choking the engine and then the muffler would have just been too much for your car to tolerate. Just spitballing.

Yep that's not an issue...

Thinking I would make more power... I dyno tested:
A) my 2650 setup with stock exhaust headers through stock 4 cats = 808.97rwhp/722.14 rwtq (dyno conditions 64*F, 30.21 in-Hg, 27% humidity)

against...

B) my 2650 setup with ARH 2" headers, cerakoted, no cats, 3" collectors and all that jazz = 836.55rwhp/748.43 rwtq (dyno conditions 66*F, 30.17 in-Hg, Humidity 24%) *without the Magnaflow muffler *

so imagine my surprise when doing this muffler I went backwards.
But, yeah I pulled all the restrictions out of the exhaust just so I didn't cook anything when doing more intense track time. I also proved that I wasn't as choked off as we all guessed I could have been with the stock setup.

And the math supports that (re: 2.5" x 2 for exhaust vs 3" x 2 -> 1 x 3" choke point)

[Z OH 6]

Originally Posted by airtroop01

Yep that's not an issue...

Thinking I would make more power... I dyno tested:
A) my 2650 setup with stock exhaust headers through stock 4 cats = 808.97rwhp/722.14 rwtq (dyno conditions 64*F, 30.21 in-Hg, 27% humidity)

against...

B) my 2650 setup with ARH 2" headers, cerakoted, no cats, 3" collectors and all that jazz = 836.55rwhp/748.43 rwtq (dyno conditions 66*F, 30.17 in-Hg, Humidity 24%) *without the Magnaflow muffler *

so imagine my surprise when doing this muffler I went backwards.
But, yeah I pulled all the restrictions out of the exhaust just so I didn't cook anything when doing more intense track time. I also proved that I wasn't as choked off as we all guessed I could have been with the stock setup.

And the math supports that (re: 2.5" x 2 for exhaust vs 3" x 2 -> 1 x 3" choke point)

You still lost me when you said you went backwards with the Magnaflow muffler. It was never dyno tested again with the muffler unless I missed that somewhere. Looking at what you posted above, it looks like you had a nice gain from the ARH 2" headers and no cats, 27'ish whp compared to the stock manifolds and stock cats.

[Joshinator99]

Originally Posted by airtroop01

Part number 12469 - I had talked to the engineers at Magnaflow and requested the internal schematic of the muffler. They confirmed that although the website shows an X is is indeed a Y

If you look at the attached schematic, lower right corner is #12469

They mentioned they have other mufflers that indeed have an internal X
But this form that fits in the tunnel with a 5x8” and variable length doesn’t exist with them with an X. They are typically wider.

Again passing what info I got from the tech.
I really wanted it to work out for me but it is what it is.

As an aside, I installed the 3” in out MBRP resonators and while the sound is louder/more aggressive… I was able to go full WOT, full power and breathed a sigh of relief. Still need to figure out a quieter solution for certain tracks but if I am cruising around and don’t jump on the throttle it’s quiet enough and quite reasonable.

Thanks for sharing @airtroop. Not sure why those knuckleheads at Magnaflow don’t post that on the website so that you can see it *before* you buy it lol!

I will probably try pushing my setup bit harder with the Magnaflow still in place as I approach 1K WHP and will keep a very close eye on this… if I reach a point where it looks to be restrictive (like in your case), then I’ll do something different. It’s only money.

[1badtie]

Following as I plan on adding Headers in a few months.

[1badtie]

Has anyone else posted some sounds clips on YouTube? I am pretty sure I watch all that were on there already which isn't much.

[6spdhyperblue]

Order the muffler from summit that katech tested, no question there.

[BlancoPopular]

Originally Posted by 6spdhyperblue

Order the muffler from summit that katech tested, no question there.

Do you happen to have a part number or link to the muffler?

[Z OH 6]

Originally Posted by BlancoPopular

Do you happen to have a part number or link to the muffler?

Its on the previous page or two.

[Katech_Zach]

It isn't exactly simple physics with the dual y vs x pipe. You dont have two full 3" pipes flowing the max possible volume 24/7 into a merge. An engine fires exhaust pulses, so you are getting pulses of exhaust that alternate between the two sides. The purpose of an X-pipe is to theoretically help the scavenging effect of the pressure differential created by the exhaust pulses.

I will say, with this increase in back pressure, you will need to get your car tuned around it. I wouldn't be surprised if it created drivability quirks on a non-revised tune.

If you want a muffler that will give the same effect as the magnaflow, with a much better "X" internal design, for less price, use the following jones muffler MF2469 (pics in page 12 from my last post): https://www.summitracing.com/parts/j...4aAsryEALw_wcB

A-B tested it on a car making over 850rwhp. It resulted in no loss in power, and made an off-road ARH/Borla Atak system sound great

[09GXP]

Originally Posted by Katech_Zach

It isn't exactly simple physics with the dual y vs x pipe. You dont have two full 3" pipes flowing the max possible volume 24/7 into a merge. An engine fires exhaust pulses, so you are getting pulses of exhaust that alternate between the two sides. The purpose of an X-pipe is to theoretically help the scavenging effect of the pressure differential created by the exhaust pulses.

I will say, with this increase in back pressure, you will need to get your car tuned around it. I wouldn't be surprised if it created drivability quirks on a non-revised tune.

If you want a muffler that will give the same effect as the magnaflow, with a much better "X" internal design, for less price, use the following jones muffler MF2469 (pics in page 12 from my last post): https://www.summitracing.com/parts/j...4aAsryEALw_wcB

A-B tested it on a car making over 850rwhp. It resulted in no loss in power, and made an off-road ARH/Borla Atak system sound great

You wouldnt happen to have any sound clips would you?

[Z OH 6]

Originally Posted by Katech_Zach

It isn't exactly simple physics with the dual y vs x pipe. You dont have two full 3" pipes flowing the max possible volume 24/7 into a merge. An engine fires exhaust pulses, so you are getting pulses of exhaust that alternate between the two sides. The purpose of an X-pipe is to theoretically help the scavenging effect of the pressure differential created by the exhaust pulses.

I will say, with this increase in back pressure, you will need to get your car tuned around it. I wouldn't be surprised if it created drivability quirks on a non-revised tune.

If you want a muffler that will give the same effect as the magnaflow, with a much better "X" internal design, for less price, use the following jones muffler MF2469 (pics in page 12 from my last post): https://www.summitracing.com/parts/j...4aAsryEALw_wcB

A-B tested it on a car making over 850rwhp. It resulted in no loss in power, and made an off-road ARH/Borla Atak system sound great

Thanks for this post Zach and this makes perfect sense otherwise some of us running the Magnaflow muffler would be choking their car to the point that it would be very noticeable and quite frankly its not. I do think it might be a restriction at a certain power level for sure but not sure what that power level is, much like the stock crushed pipes eventually become a restriction but its a lot more power than most people realize. That being said, you're right, the Jones muffler is a safer bet if given the choice between the two.

[Katech_Zach]

Originally Posted by 09GXP

You wouldnt happen to have any sound clips would you?

I do not have any sound clips unfortunately, but i will be putting this muffler on my personal ZL1 that has an ARH off road system + borla S-type.

I see that you're in michigan, so you can swing by katech and take a listen when i get them on within the next month.

[SOCAL.M6.ZLE]

Originally Posted by Katech_Zach

It isn't exactly simple physics with the dual y vs x pipe. You dont have two full 3" pipes flowing the max possible volume 24/7 into a merge. An engine fires exhaust pulses, so you are getting pulses of exhaust that alternate between the two sides. The purpose of an X-pipe is to theoretically help the scavenging effect of the pressure differential created by the exhaust pulses.

I will say, with this increase in back pressure, you will need to get your car tuned around it. I wouldn't be surprised if it created drivability quirks on a non-revised tune.

If you want a muffler that will give the same effect as the magnaflow, with a much better "X" internal design, for less price, use the following jones muffler MF2469 (pics in page 12 from my last post): https://www.summitracing.com/parts/j...4aAsryEALw_wcB

A-B tested it on a car making over 850rwhp. It resulted in no loss in power, and made an off-road ARH/Borla Atak system sound great

Hey Zach, you bring up one of my main concerns about adding this 3rd muffler in... that it was adding too much back-pressure, and hurting performance. If not at my current HP levels, perhaps once i settle around 700-750rwhp?


What are your thoughts, and is there a way to verify this through HP tuners?