Coil form

Hello All,
My latest coil secondary is wound on a 6.75 od. schedule 80 pvc pipe 20 inches
wind length with #24 magnet wire, preped with poly before and after winding.
Input is 12000 volts -at-120ma. With a variac I can get up to 44 inch
streamers. I wound this with the thick wall pvc before I knew to use thin
walled coil forms. My question is would it be worth while to wind another
coil form of  plexiglas  and possibly use larger wire. I believe my primary
could be tuned for these changes. Would the gain be significant? Thanks.

Brad McPeak