Ride with a bunch of M1000 about every other weekend. A couple have the Speedwerx and a couple have the SLP. In most cases the SLP will out perform the Speedworx. From what I have seen, it takes porting to make the Speedwerx run with the SLP. I dont know who makes more power, but the SLP's seam to be a better performing product. And your right, they fit better. One of the guys just ditched his Speedwerx for the SLP. We ride 6000-10,000ft, All 163" tracks. I have run them both. When they are both dialed in, they run real close, but the SLP just seem to be a bit better. They seemed easier to dial in as well. Maybe that is just because SLP is located in the west, not sure.