Is there an electric choke conversion for a six pack setup???

I'm currently testing with 12v 40w ceramic cartridge heater. They just lay in the choke well. I tested it with a 13.4 volt supply at 3.5 amps. The choke fully opened in 3:56 min
I'm going to test next with a 30watt cartridge. Wiring would be to keyswitch "on" and battery neg. This is still in the testing phase. I"m trying to get the heat down to @ 195degrees. I am not willing to cut my intake! heaters are $9.00.