Short version: awesome power, but very frustrating for beginners.
Long version: I really do love the spring, but the difficulty on this was out of my league. I'm not an affluent modder (mostly installing hammershot spacers, Perses hoppers, and a couple of Nexus Pro springs), but I saw this and felt like it was worth trying for the increased power. I see why Luke is the pro and able to call this medium difficulty, but I had a terrible time closing up the blaster with this spring in. It kept popping out of place because of the strength and I couldn't get everything lined up while holding the tube in place. After 6 frustrating attempts and realigning all the tiny pieces that kept flying everywhere, I finally closed it up and got to blasting. I do wish I would have waited for a mod video for some tips on closing it up.
1. Made the blaster so much better!
2. Even better when paired with the 3d printed hop-up.
3. Very difficult installation for a beginner like me.