Why the hard feelings about the 6.0 Chevy?

Thunderbolt wrote:
I have an H pipe, but I can still tell the difference.

Stefonius wrote:

Thunderbolt wrote:
I have an 03 with the 6.0 and the worst upgrade I did was true dual exhaust. I lost power down low compared to the stock exhaust. I will go back to a single 3" when I need exhaust.

That's because of the Chevy's firing order (1-8-7-2-6-5-4-3). Cylinders on the same bank fire concurrently (2-6), while cylinders on the opposite bank fire with a long pause between two of them (7-x-x-5). This creates uneven pressure waves through a true dual exhaust system and disrupts the flow of gasses. Install a collector "Y" or "H" pipe in the system to even it out.

There's also the concept called scavenging which is how the flow and pressure waves within the exhaust system affect the flow of intake air during the brief time when both the intake and exhaust valves are open. When you alter or open the exhaust system you can affect scavenging in a negative way for lower RPM in trade for improved flow at higher RPM.