Holley TBI

I'm not going to run the system. I just barely got my 550 dollar quick fuel carburetor dialed in, Took me awhile with working full time and all I had to go by was reading plugs and feel.
But I got my engine running the best that it's ever been since I've had it. I'm not fouling plugs, the plugs look good, good grey/tanish color, no miss fires, no hiccups thru out the throttle.
I was just hoping to find out what this stuff is and find out what it's worth and how sought after it is. I'm most likely going to sell it.