To increase the power of each stroke, you need to focus on a nice high elbow catch and pull, and the speed that you pull. With each pull, you want to maintain about a 45-95 degree bend in your elbow while keeping the elbow fairly high relative to the surface. You do not want to straighten your arm and try to touch the bottom of the pool, a misconception that many swimmers have.
The part of generating a powerful stroke is the speed at which you pull, so increasing pull speed will obviously directly relate to how fast you swim. A slow cadence will not help if you are not generating lots of power. To improve power, I like do several things. For one, I include sets of catch up and switch drills. In catch up, you slow down your stroke so your emphasis is completely on a nice entrance and quick high pull for each arm as well as a nice strong rotation of the hips generated from the core. In the switch drill you must focus on rotating your hips in a fast and efficient manner to propel you forward.
Implementing paddle use is also helpful in building power but only if you have strong shoulders since paddles can cause or aggravate rotator cuff problems. I particularly like the Finis paddles since they will not work properly if your form is off. They also do not stress my shoulders at all.
Hopefully, extending your reach as well as increasing power will help you shoot a sub par in your next SWOLF set.
Train hard, recover harder
Coach Chris and Kev