do i realy need shims with my dark magic i have a konkave bearing
You really don’t “need” shims. They just make your gap larger. Ask the question to yourself: “Do I want a larger gap?” If yes, shims would do you good. If no, you don’t need shims. There’s a few different shim setups. Some people use two red. Some people one red and one grey. WHile some people use two grey. SHims don’t cost that much anyways, so you can buy a few.
i decided i need shims when i wanted to learn skin the gerbil and it kept hitting my finger because too many strings were in the gap 
shims rule, metal merc shims from yoyoguy.com work great, and you get 3 different sizes. I use the thickest, 1 on each side, on my speedmaker so its very unresponsive
Shims aren’t like a must have in a yoyo its just what everyone elso said, a thing to make your gap bigger. I never tried shims because I never felt the need to use one but I heard a konkave can rip or tear the red or grey shim so you would have to get the metal oneswhich are more expensive. If you feel like you need a bigger gap and less response then use shims.
I don’t exactly know, but I’ve heard that Dual O-Rings are dead unresponsive. My Hybrid Hitman can be responsive and unresponsive wether if I tighten the gap or not. Its weird.