I didn't post this here, but I had terrible flight from broadheads on my Killer Instinct 350. I was not using their bolts but Carbon Express, which are fine right? Maybe, but not for my xbow, you can read it all
here. Spine matters in Bolts too.
To summarize for those that don't wish to read the entire story, The CE bots are under spined and bend too much and catch air causing planing. I bought KillerTech Pro bolts and a great broadhead flight. I also got perfect field tip flight and got flatter shooting bolts all around.
I out the bolts on my spine tester and found the CE bolts to be twice as soft in spine as the KillerTech bolts!
KillerTeck Pro 20" bolts with half moon nocks – 4°
Wicked Ridge boltsmade by Easton – 6° These have Omni nocks and I could test them on my bow, but they work great on Sonya’s WickedRidge
Carbon Express Pile Driver bolts – 9°