Killer 9 is a great engine for the price! I have almost 2 gallons on mine including the break-in (gallon). Engine is still super tight that you struggle to turn the flywheel over when mounted in my truggy.

My setup is:
7mm insert
2045/192mm pipe/header
Byron %25 Pro

(ditch the 8mm insert it comes with for a 7mm, BIG difference in runtime!!)

Last week I was able to get almost 10 mins on a pit.
I ran a 20 min. Main on one stop and ran out of gas after I crossed the finish line for my last lap. Luckily I had a nice lead on third to hang on to my 2nd place finish. The engine was cold, I don't know what the actual temp was but I would guess about 190'.

I will definately buy another one when this one dies.