Mike R is spot-on.

Technically, however, he transplanted the engine into the car that already had the transmission, instead of mating the transmission to a factory SRT-6.

As recall, updates fell short as he neared the end of the project.

Generally speaking, you won't gain much from the swap. While it's true that rowing the gears is more fun (I subscribe to that school of thought), it's also not nearly as fast and safe as the way the AMG auto can shift. If you are an EXCELLENT driver, you'll only match the shift-speed of the auto. I hazard to say you won't beat it though. You CAN completely manipulate when, where, and why you shift, which is always fun. And the six-speed is also roughly 1/3 the weight and no maintenance required.

Also, the auto trans is much tougher. The manual is good to roughly 400 horsepower, but the auto is good for almost 700.