The point of the original post was simply that there is a side benefit of weight loss associated with some exhaust modifications.
Roughly speaking a weight reduction of ten pounds would be equivalent to a 1.5 hp gain.
Some exhaust systems used to replace stock do indeed weigh (ten pounds or more), less than the stock does.
That would be a relative gain of 1.5 hp; in addition to the gain you receive due to the functional aspect of the part. Senior service at HD in Crystal River said they see 5 and 6 hp gains from stage 1 mod's commonly. If that is the case choosing lightest as well as best performance could increase yield by the 1.5 hp suggested. 1.5 hp is about 25% of the total gain to be had from the entire stage 1. Not a small consideration... For those that state lose weight or (paraphrase) leave your significant other home That is when the advantage is most needed.
Loading the bike with uneeded extra weight makes it slower and less powerful.
Taking your lady for a ride, Priceless...

 

Oh, I didn't realize this was actually a SERIOUS question at first.

To answer the question:

My stock mufflers that have been laying around in my garage for 3 years weight 13 pounds.

The cycle shack mufflers that I recently replaced with new pipes weight 7 pounds.

Those results are from the very low tech method of holding the pipes, while standing on digital bathroom scales and subtracting the tare weight.

 

I liked your first answer better.