I did a few dyno pulls to test the changes with these pipes on my stock truck. I tested it completely stock, and then tested it with a tune. After that I tested the truck with the new pipes on a stock tune, and then with a custom tune. There was not a large gain in power.
On my modified truck I do believe they contributed to a noticeable power gain, but I did not test them separately to have the dyno numbers.
I will add the charts in an edit to this post shortly.
See the last photo for explanation of all these charts.
The truck made less power and torque with the pipes installed.
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