You are on the right track. Race gas territory for sure. Get some 22's and it should put you back in pump gas range. And you should be able to give it a bit of timing.
This is all to common. Guy hears how cool banshees are. Buys one stock and gets beat up. So he either red neck engineers EVERYTHING! Or, buys a bunch of good parts, slaps them together with out ever thinkin of over all set up. Then they start it up and it rattles plugs out, burns holes in pistons, etc. But it's really "cuz banshees are unreliable". Has nothing to do with the bit with under fueling, not jetting, throwing timing at something already backing plugs.