I'm helping a friend re-do his 485 cheetah. Same problem, detonation and backing plugs out. I sent his domes out to Tim at Titan Racing with some specs about his setup and where we ride, what fuel he wants to run, etc. Tim will have new domes back to us next week, ready to run. Sounds to me like you sent your stuff to the wrong folks. Do a little research ahead of time & you could have saved yourself a huge headache down the road.
Best of luck with Shitrinity.