Differences in intake length can affect the power output just like differences in exhaust length-witness the machines that feature variable-length intakes to produce power at varying rpm. If the spun-aluminum aftermarket stacks are the same length as the stock plastic , I would doubt there is much of an improvement. If they are different, they could possibly move the powerband around without producing any more peak hp
Years ago, some guys vintage racing an old Norton twin at Daytona were having trouble getting it to run well with open intakes (no filters or anything on the carbs). The machine wouldn't pull max rpm and get up to its potential top speed. They called Leo Goff, the famous Norton dragracer and he told them, "You have the typical Norton midrange miss. Get some velocity stacks to increase the intake length and your midrange will return and the motor will pull through to max rpm." They searched all over town and couldn't find stacks for the ancient Amal carbs. Finally, in desperation, they cut the bottoms and tops off some used beer cans, stuck them on and went out for practice. For the first time, that old twin wound out all the way to redline and they got the speed they geared for on the banking without losing tractability on the infield
I actually tried this and it worked! That was when I found out I needed to replace the all-metal stock clutch with some Barnett fiber friction plates, because when the motor hit 4500 rpm, the torque came on so strong it made the clutch slip, something I had read could happen when you increase power over stock levels.
So when midrange stacks were mentioned for the 14, it tripped my mental trigger. As much as I love my new ride, it doesn't have the grunt of my old one, so anything that might give me some of that is of intense interest.