Exhaust Pressure Testing

[K4fxd]

The hardest part is getting the driver’s side of the car high enough.

The driver side is easy? looks like the manifold has to come off with the cat.

I thought that required removing the steering shaft and motor mounts.

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[Exploded_Muffin]

And in comparison to the tru x?

Tru-x have been the quietest for me.
60661 were a step above the tru-x.
Stainless bros were several steps above the tru-x and 60661, not in the same category volume wise at all

 

[K4fxd]

well over 90 lb/min flow.

So 2 or 3 psi at a N/A 48lb ish rate?

 

[GregO]

So is the 60661 or the stainless bros res louder? I have the Xmod system. Catless, 2.5 connectors at the moment, tru -x resonator, then rest of the exhaust

My stainless bros were significantly louder than my 60661s. You mileage may vary...

60661 = internal H crossover = Quieter
Stainless Bros. = NO crossover = Louder

 

[engineermike]

The driver side is easy? looks like the manifold has to come off with the cat.

I thought that required removing the steering shaft and motor mounts.

Both sides are rather easy, tbh. On the drivers side you pull the sleeve clamp at the resonator and the band at the cat outlet. That s-pipe just rotates and slides out. Then it’s just the steering column (1 bolt) and 8 header bolts, all of which can be reached with a ratchet. Once the bolts are out the header drops out but the car has to be fairly high to allow it to rotate out.

 

[engineermike]

60661 = internal H crossover = Quieter
Stainless Bros. = NO crossover = Louder

Yes, adding an H-pipe to the stainlessbros made a big difference. The problem with the borla 60661 is that it internally necks down to 2.5”.

 

[TEXAS HEAT]

It’s a weekend car but it’s street driven 99% of the time. Hopefully the 60661 with turndowns immediately after the resonator is at least tolerable as far as loudness goes.

Tru-x have been the quietest for me.
60661 were a step above the tru-x.
Stainless bros were several steps above the tru-x and 60661, not in the same category volume wise at all

This has been my experience as well.

Magnaflow Tru-X being the most quiet paired with factory cat-back
Borla 60661 - being more subtle at low rpm, but pretty loud above 4000rpm and any real throttle when paired with the Borla S-Type 3" cat-back
Stainless Bros... - I haven't used, but I have no doubt that you're correct.

 

[engineermike]

How much of that restriction are the cats though? I'm FFE, so I'm hoping that I'm a little closer to being under the 5psi back pressure once I get rid of the 2.25" restriction.

Iirc the stock cats only add about 3.5 psi backpressure at 10 psi boost, and 4.5 at 15 psi. They aren’t as bad as most believe them to be.

Id have to go back and verify, but I was surprised to see that just the stock 2.5” S-pipe was adding 2 psi in that short
bit of piping.

 

[TEXAS HEAT]

Yes, adding an H-pipe to the stainlessbros made a big difference. The problem with the borla 60661 is that it internally necks down to 2.5”.

Yes sir, the 2.5" is definitely the most restrictive part when paired with 3" everything else.

I'm going to move forward with removing with the 2.25" bottle neck and use the 3" to 2.5" reducers to connect to the Borla 60661. I'll take the extra 2psi reduction in back pressure and hopefully when combined with the MAK delete pipes it will be enough to allow it to flow without significantly increasing noise and drone.

 

[engineermike]

So 2 or 3 psi at a N/A 48lb ish rate?

Probably less. I don’t have data to prove it directly, but I believe the stock complete exhaust is in the neighborhood of 5 psi at the collector at the stock flow rates.

 

[GregO]

Yes, adding an H-pipe to the stainlessbros made a big difference. The problem with the borla 60661 is that it internally necks down to 2.5”.

Yup that’s why I sold the one we had left over.

 

[Proshop]

That sounds great to me! Thats the borla atak active and dual in dual out resonator right?

And i forget if you have longtubes or are catless. So many exhaust videos

Borla atak w/ active, stainless bros dual in dual out 3” muffler and no kitties/ off road.

 

[K4fxd]

I don’t have data to prove it directly, but I believe the stock complete exhaust is in the neighborhood of 5 psi at the collector at the stock flow rates.

Is that the 18 up? My 17 has 2.250 tubes coming off the cats. My old header design notes say 2.25 tube is good up to 230 hp so 460 on a V8 dual. This seems to be the wall I'm hitting.

 

[engineermike]

Yea I was referring to 18+

 

[Zelek]

Borla atak w/ active, stainless bros dual in dual out 3” muffler and no kitties/ off road.

This is the setup I'm going to try to run on my Mach 1. I've got the GT500 Borla Atak on and Kooks green catted headers on order. I'll get the 3" adapters for the headers. I was thinking of swapping out the Crossfire with the stainless bros because it is going to be insanely loud but it might be pointless due to the fact that it's still really loud even with the Stainless Bros 3" in/out in there. It's really the only 3" option for the Mach 1's currently aside from going Corsa which has smaller tips than the OEM Mach 1 ones.

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