Nah, if you take a signal from the earth side of the coil & it bein negative pulse it's make the engine miss & cut out !!

Which would incediently increase the effect of the flamer but at the cost of the engine !! lol

It mainly flames on the over run, but if you had a switch from your ignition coil it'd flame any time you put it on !! Mainly cos the engine missfiring due to no spark !! lol

Oh & it wouldn't really matter where you took the live from as the coil as a ignition switched live anyway & only discharges with the earth.

Don't do it !!

jb