[NY135ivishnu]

Originally Posted by _RS4_

The increase in power occurs when removing the primary kats in the downpipes, if you remove the secondary kats you will not get a significant increase in power because you still have two restrictions on the top of the exhaust line. Replacing the primary kats with de-kat dps or 200 cells kats will give you a handful of hp.

If each set of cat gave you "20hp" and we have two sets, what would the total be ? Also just the weight of the AA pipe compared to the stock would be or could be a good reason for getting the mod.

OP is this something that's been done? Weight comparison on stock mid and AA mid?

[VIERsr]

Yes 20 hp with dekat dps, 18 more with mid pipe and 17 with air intake, 55 hp without ecu tune LOL

[mike@x-ph.com]

Originally Posted by _RS4_

Yes 20 hp with dekat dps, 18 more with mid pipe and 17 with air intake, 55 hp without ecu tune LOL

You can laugh all you want, but the dyno is posted for you to see.

Unless you are accusing AA of cheating, im not sure what point you are trying to make?

Instead of being sarcastic, i recommend you prove your point by showing a proof where the midpipe did not add any power.

[Muncher]

Originally Posted by Ceramic Rabbit

Im not sure about that, I thought the main benefit of the mid was basically just the sound since it consolidates two 3 inch pipes into a single 3.5.

If area is Pi r2, then 2 pipes at 3” has greater cross sectional area than one pipe at 3.5”. Am I missing something. 3x3x2x22/7=56.57 sq inches vs 3.5x3.5x22/7=38.5 sq inches.
The stock system 2 by 3” inch pipes has a 50% higher flow capability. So more going on here with deletion of restriction which is not an apples to apples comparison. I make assumption here stock mids are 3”. That’s impressively large.

Over in M6g Mustang forum, the arguments are endless about cutting in H pipe sections into the GT’s parallel mid pipes to achieve a low bellowing note, or inserting X pipes instead for slightly better flow but these can sound raspy at higher rpms.

Any-one thinking of just putting one or more cross tubes between the two std parallel mid pipes to balance the note and achieve the single pipe tone claims but with a higher flow potential?

[Kuervers]

Originally Posted by Muncher

If area is Pi r2, then 2 pipes at 3” has greater cross sectional area than one pipe at 3.5”. Am I missing something. 3x3x2x22/7=56.57 sq inches vs 3.5x3.5x22/7=38.5 sq inches.
The stock system 2 by 3” inch pipes has a 50% higher flow capability. So more going on here with deletion of restriction which is not an apples to apples comparison. I make assumption here stock mids are 3”. That’s impressively large.

Over in M6g Mustang forum, the arguments are endless about cutting in H pipe sections into the GT’s parallel mid pipes to achieve a low bellowing note, or inserting X pipes instead for slightly better flow but these can sound raspy at higher rpms.

Any-one thinking of just putting one or more cross tubes between the two std parallel mid pipes to balance the note and achieve the single pipe tone claims but with a higher flow potential?

Isn't stock pipe 2x2.5? You aren't taking into account the lower coefficient of friction of a single 3.5 either

[Kuervers]

The flow loss through the cats is prob 5hp alone

[mike@x-ph.com]

Originally Posted by Kuervers

The flow loss through the cats is prob 5hp alone

How do you like the exhaust sound after installing the AA midpipe ?

[Kuervers]

Great have car parked winter so cant really enjoy it much but sound is much cleaner and deeper with some turbo spool noise. Bmw did a good job on the m2c's rear section.

[mike@x-ph.com]

Originally Posted by Kuervers

Great have car parked winter so cant really enjoy it much but sound is much cleaner and deeper with some turbo spool noise. Bmw did a good job on the m2c's rear section.

Awesome

[Bee Pee]

Originally Posted by Muncher

If area is Pi r2, then 2 pipes at 3” has greater cross sectional area than one pipe at 3.5”. Am I missing something. 3x3x2x22/7=56.57 sq inches vs 3.5x3.5x22/7=38.5 sq inches.
The stock system 2 by 3” inch pipes has a 50% higher flow capability. So more going on here with deletion of restriction which is not an apples to apples comparison. I make assumption here stock mids are 3”. That’s impressively large.

std s55 mids are dual 2.5" diameter or radius 1.25" for both pipes so CSA is 1.25 x 1.25 x 2 x 22/7 = 9.82 sq in

AA s55 m/pipe is single 3.5" diameter or radius of 1.75" so CSA = 1.75 x 1.75 x 22/7 = 9.625 sq in

CSA reduction of ~2% but this likely to be offset by less turbulent flow in large ID single m/pipe, compared to dual pipes, due to smaller circumference = less drag/friction at the interface where gas flows close to pipe ID surface.

[Muncher]

Ah ha- thanks for correcting my calcs. I used dia not radius and as you indicate pipes are 2.5".

So the 3.5 " is smaller and with friction issue maybe line ball. So this alone isn't a driver of a power increase IMHO. An H pipe section added in may achieve similar note change.

I liked the exh note of the demo I drove so not planning change on mine at this time
Cheers

[chmura]

Not a good time for California residents.

[David@ActiveAutowerke]

Originally Posted by Muncher

Ah ha- thanks for correcting my calcs. I used dia not radius and as you indicate pipes are 2.5".

So the 3.5 " is smaller and with friction issue maybe line ball. So this alone isn't a driver of a power increase IMHO. An H pipe section added in may achieve similar note change.

I liked the exh note of the demo I drove so not planning change on mine at this time
Cheers

Volume isn't the only factor when determining flow.

Overall volume is less but so is the overall friction with the smaller surface area. However, the main contributing factor to the power increase is the increased velocity. By mixing both banks almost immediately after the downpipe, we can take advantage of the Venturi effect as demonstrated below. This will promote high exhaust gas speed which helps reduce spool time and increase overall output.

[CosmosMpower]

Originally Posted by chmura

Not a good time for California residents.

CA is a hell hole. If you're a car or gun enthusiast it's pretty much the worst.

[pz619]

Originally Posted by chmura

Not a good time for California residents.

Said it before, and I'll probably say it again (not picking on your). The only change is that it's no longer a correctable violation. The actually exhaust law has been in place since the late 50s and updated it 1998. So if you didn't get a ticket last year, you won't this year. Also, if it's that big of a deal, keep the stock exhaust and if you get a ticket, swap and get tested.

[MR.]

Originally Posted by CosmosMpower

CA is a hell hole. If you're a car or gun enthusiast it's pretty much the worst.

Nothing is as bad as Germany or Switzerland right now

MR

[mike@x-ph.com]

Originally Posted by MR.

Nothing is as bad as Germany or Switzerland right now

MR

We cant even ship LED bulbs to Germany anymore

[Ceramic Rabbit]

Originally Posted by David@ActiveAutowerke

Volume isn't the only factor when determining flow.

Overall volume is less but so is the overall friction with the smaller surface area. However, the main contributing factor to the power increase is the increased velocity. By mixing both banks almost immediately after the downpipe, we can take advantage of the Venturi effect as demonstrated below. This will promote high exhaust gas speed which helps reduce spool time and increase overall output.

That doesn't really seem like a viable comparison considering the pipes aren't attached to the same thing. The OEM are in a muffler and the others arent attached to anything which I'm sure would have an affect on air flowing in or out.

[cpxchewy]

Originally Posted by pz619

Said it before, and I'll probably say it again (not picking on your). The only change is that it's no longer a correctable violation. The actually exhaust law has been in place since the late 50s and updated it 1998. So if you didn't get a ticket last year, you won't this year. Also, if it's that big of a deal, keep the stock exhaust and if you get a ticket, swap and get tested.

The new law isn't a fixit ticket anymore. Just a straight fine.

[David@ActiveAutowerke]

Originally Posted by Ceramic Rabbit

That doesn't really seem like a viable comparison considering the pipes aren't attached to the same thing. The OEM are in a muffler and the others arent attached to anything which I'm sure would have an affect on air flowing in or out.

The very little amount of air flowing from the demonstration will not be affected by a muffler, especially since the OEM muffler is straight through, and the stock mid pipe has two cats and a resonator in it. Did you not notice the rag being sucked in to one bank on our mid pipe? This is not possible with the stock exhaust since the banks don't mix until much further back when the exhaust gases have already slowed down.

[hellrotm]

Originally Posted by cpxchewy

The new law isn't a fixit ticket anymore. Just a straight fine.

$1k fine...crazy.

There have been people already pulled over and fined for a completely stock exhaust. Now that individual has to waste his time to go to court to prove his car is stock.

Grew up in SoCal, I no longer tell people I am from there. That place has become embarrassing. Much bigger problems to deal with than loud exhausts.

There are police units actively searching just for loud exhaust right now. Money maker.

[Ceramic Rabbit]

Originally Posted by David@ActiveAutowerke

The very little amount of air flowing from the demonstration will not be affected by a muffler, especially since the OEM muffler is straight through, and the stock mid pipe has two cats and a resonator in it. Did you not notice the rag being sucked in to one bank on our mid pipe? This is not possible with the stock exhaust since the banks don't mix until much further back when the exhaust gases have already slowed down.

Why would air be flowing the wrong direction out of the stock pipes then? That doesn't make any sense to me.