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Posted
8 minutes ago, GETGONE said:

Yes, muffler and flapper valve(only had one on my truck in front of muffler) and replaced with Magnaflow straight pipe. Unless you count changing the oil at 1000 miles with Mobil 1 and a Purolator Boss filter!

I knew stock exhausts always choked down engines, and it's nice to see how the engine wakes up by letting it breathe. What muffler did you go with?

Posted

NO muffler, just the Magnaflow straight pipe. Resonators are still in place in the back. The 6.2 has real resonators and not the screened junk the 5.3's have.

Posted

The stock exhaust has no real restrictions. The size of the pipes can support far more power than the engine makes. Just remember that even a corvette/camaro makes more power with roughly the same size exhaust.

 

The torque spikes make sense with it not being able to hold a gear. Looks like one run was up in the 390's for torque, that would be more understandable with drivetrain loss factored in.

Posted
10 minutes ago, GETGONE said:

NO muffler, just the Magnaflow straight pipe. Resonators are still in place in the back. The 6.2 has real resonators and not the screened junk the 5.3's have.

You should do a video on how it sounds! Im curious

Posted
8 hours ago, GETGONE said:

NO muffler, just the Magnaflow straight pipe. Resonators are still in place in the back. The 6.2 has real resonators and not the screened junk the 5.3's have.

I have the Corsa Catback system and when my father (mechanic) and I removed the stock exhaust he could t believe the restrictions the 2 valves had on stock exhaust even when open. It was still almost 50% restricted.  
IDK the numbers on my truck with 6.2L but it accelerates way better than before. 

 

Awesome numbers by the way. Congrats. 

Posted
8 hours ago, CamGTP said:

The stock exhaust has no real restrictions. The size of the pipes can support far more power than the engine makes. Just remember that even a corvette/camaro makes more power with roughly the same size exhaust.

 

The torque spikes make sense with it not being able to hold a gear. Looks like one run was up in the 390's for torque, that would be more understandable with drivetrain loss factored in.

The 2 flapper valves are a huge restriction. If you remove them and add a muffler or straight pipe then yes, I agree. It is almost the same as my Corsa Catback in terms of the bend and diameter.  You just don’t know if you will have the annoying drone or not with straight pipe or adding muffler. 

Posted
15 hours ago, CamGTP said:

I could possibly believe that horsepower number though it's a little high but that torque number isn't accurate. Plus we can't get the 10 speeds in the correct gear on a dyno with the stock driveshafts and limited wheel speed. That correction factor on that dyno is a little out of whack.

 

13 hours ago, GETGONE said:

 

2021_Silverado_Dyno.png

 

 

 

If you add up all three HP and then all 3 torque and divide by 3 to average, 365.2hp, 420.76tq.  

Posted

Just for those that don't know what the flapper valve looks like inside the pipe. You can see the heavy bottom side at the top of the picture on the OEM muffler after I cut it out of the pipe. That tiny hole is all that is open unless it has enough exhaust pressure to overcome the tension on the spring that is on the outside of the pipe. Even if you do the "hack" to hold the valve open, you still have that huge hunk of metal blocking the flow in the pipe.

 

 

Muffler_Flapper.jpg

  • Like 1
Posted
On 3/28/2022 at 5:54 PM, GETGONE said:

Just for those that don't know what the flapper valve looks like inside the pipe. You can see the heavy bottom side at the top of the picture on the OEM muffler after I cut it out of the pipe. That tiny hole is all that is open unless it has enough exhaust pressure to overcome the tension on the spring that is on the outside of the pipe. Even if you do the "hack" to hold the valve open, you still have that huge hunk of metal blocking the flow in the pipe.

 

 

Muffler_Flapper.jpg

Do you have any part numbers or references/links to tubing to replace the section(s) that holds the flappers once they are cut out?  Thanks. 

Posted

NO, since I cut out the muffler and flapper. If you're looking for just cutting out the flapper, it would be best to take it to a muffler shop. The 6.2 uses 3" pipe. I'm not sure what the 5.3 uses. I'm guessing 2.5".

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