Thanks, I'm glad you appreciate it! It's always nice to encounter someone with similar design opinions. :)
This mod is a deliberate reversion (or you could say callback) to the flamethrower ammo recipe before oil processing was changed. You used to get all three oil fractions from basic processing; advanced processing unlocked better yields and the ability to crack, but since you could get light/heavy without it, it wasn't a prerequisite tech for flamethrowers. When heavy and light oil were moved to be advanced processing only, flamethrower ammo had its recipe changed (from light+heavy+steel) so it could stay in more or less the same place in progression.
I didn't want to simply change the vanilla recipe back (altering that progression), I just wanted to resurrect the old recipe. The damage bonus is mostly there to give you a reason to actually use it.
That said, adding napalm does sound cool, but I don't think its place is packaged together with this mod.