Stock mufflers...power...

[nrmustang]

Long story short, I pulled off my Flowmaster Force II axle backs and stock cat-pipe, and installed a Lethal o/r H with stock mufflers.

It threw a check engine light (I knew it would), and decided to throw the stock cat-pipe on with the stock axle backs for now.

Here's my question: Everyone swears the stock mufflers flow great, and there's no power advantage to any aftermarket axle back. However, I can tell a difference going from the Flow's to the stock mufflers. Does anyone have any hard evidence (ie; dyno sheet) proving their theory either that axle backs do/don't flow better?

I searched, but again, all theories or marketing, and little evidence. Thanks

 

[1 Alibi 2]

I have no A / B comparisons, but run stock mufflers on both cars.
11 - Kooks 1 3/4" LT's & " green " catted X pipe. ( N.J. is an inspection state )
14 - Kooks 1 7/8" LT's & " green " catted X pipe.
Both cars make reasonable hp with the stock mufflers.
.

 

[nrmustang]

Update: I now hear noticeable detonation under load. After talking with my tuner - Shaun @AED, he explained the more restrictive exhaust would cause it to run leaner. This is back and forth between emails this morning, so swapping in stock mufflers + lower power + detonation= aftermarket axle backs flow better...at least from this experience.

 

[NC85]

Bad gas?

 

[nrmustang]

Nope, see post #3.

Thanks

 

[99SSls1]

Aftermarket mufflers (most) will outflow the stock. Aftermarket are just louder then most so the stockers work.

 

[Black Sex]

Are you getting detonation or just a raspy sound from the mufflers?
I just recently installed LT's on my '11 and the stock mufflers have a raspy tone now between 2500-3500 rpm at part throttle.

 

[nrmustang]

Are you getting detonation or just a raspy sound from the mufflers?
I just recently installed LT's on my '11 and the stock mufflers have a raspy tone now between 2500-3500 rpm at part throttle.

Again, stock cat-pipe, stock axle back. No rasp. It's detonation.

 

[Harry08]

I seem to remember a few years ago Justin from VMP saying the difference between aftermarket mufflers and stockers was minimal. I believe that was with long tubes.

 

[NC85]

Welp, better save up for a new longblock then.

I'll spread the word on stock mufflers giving their stock engines Auto AIDS.

 

[Black Sex]

^x2
Have you pulled the plugs to make sure it's detonating?

 

[nrmustang]

Swapped back to the Flowmaster axle backs. Problem solved.

It's so frustrating reading that the stock mufflers flow just as well as axle backs, only to find this out. Thanks Shaun @AED. Thankfully I'm not a retard that stays in the pedal til it pops. Everything is just fine now.

 

[Speedboosted]

Pull the plugs and report back. No way your chambered flowsuckers outflow the stock mufflers by that much to make a difference that actually matters. Did you put different fuel in it since this started about a week ago?

 

[nrmustang]

Pull the plugs and report back. No way your chambered flowsuckers outflow the stock mufflers by that much to make a difference that actually matters. Did you put different fuel in it since this started about a week ago?

Dude, I don't know what to say. I last drive the car Sunday night. Noticeable pinging under load, no question. Swapped the axle back today, test drove it, and heard 2 "ticks" under load. One each during two separate pulls. But I drove it for about 10 minutes on the back roads, hard pulls, and nothing aside from that.

Now remember, I have the stock cats, and Shaun did set it up to pull timing, so hot cats could've pulled timing thus stopping any detonation. I have 26k on the clock and did my TVS/tune about 1k ago. Melting cats, I don't know. I love this car, but at this point am sick of the drama that comes with personalities and the hobby. Thanks for the input, I'll pull the plugs and see what we have.

 

[Speedboosted]

Dude, I don't know what to say. I last drive the car Sunday night. Noticeable pinging under load, no question. Swapped the axle back today, test drove it, and heard 2 "ticks" under load. One each during two separate pulls. But I drove it for about 10 minutes on the back roads, hard pulls, and nothing aside from that.

Now remember, I have the stock cats, and Shaun did set it up to pull timing, so hot cats could've pulled timing thus stopping any detonation. I have 26k on the clock and did my TVS/tune about 1k ago. Melting cats, I don't know. I love this car, but at this point am sick of the drama that comes with personalities and the hobby. Thanks for the input, I'll pull the plugs and see what we have.

Describe these ticks in more detail. Also why are the cats still on the car? You're getting to that area where they don't like to live for a while. Pending how the plugs look, I would say to toss the other mufflers back on and datalog both during some cruising and of course at WOT. You didn't happen to be logging last time when it ticked did you?

Edit- I remember the thread about the cats for you, disregard that question

 

[RedVenom48]

Hell, if you can easily remove the stock cat pipe do it and check the cats to see if they are melting down or still look honeycomb

 

[Black Sex]

My cats melted at 3500ish miles

 

[Sirraf]

Could it have been an exhaust leak?