Reviving this thread because it comes up when doing a search online and gives some misleading information on the Gibson shortie headers, so I thought I'd update it for accuracy.
I had the Gibson shorties installed on Friday (mating them up to my previously installed Gibson SS Super Truck Cat-back system), no pictures because you really can't see anything.
I got exactly what I was expecting and a little more, an even deeper rumble and a little gain in torque on the bottom end (didn't expect it to enhance the sound of the cam hitting, but it did that too?).
My truck runs like a scalded dog when you give it WOT, but at a light or just cruising at low speeds, around 1,500-2,000 rpm's if you don't give it just the right amount of gas it almost felt like there was slight stumble trying to maintain torque in lower power band?
That's completely gone now, nice smooth torque gain through the power band!
I'm happy with the Gibson shorties.
Keep in mind, headers are just a piece of the larger picture homogenized with other performance goodies finalized with a performance tune.