To make a cheap pre-heater:
Simply take some brass or copper tubing about 12 in long, coil it around your exhaust tube and either braze or JB weld it in place. You then connect the exit from your pump to one end of the tubing, and then connect the other end of the tube to your smoke tap, using some neoprene fuel tubing.

In order to keep the neoprene tubing in place take a 5-10mm length of silicone tubing and put it over the neoprene tube where it overlaps the copper. The silicone ends up acting like a clamp so the neoprene doesn’t slide off the copper.

Let me know if this is too confusing and I'll post a picture.

Once you get one of these in place you can up the smoke rate.

Also, the lower pitch prop and the more RPM you can get the higher rate and the better the smoke will look.

BTW: I didn't have much luck with ATF when I did some experimenting. It seemed that decil fuel alone did pretty well, and baby oil worked even better. You might want to try it without the ATF.

If you get some super-dri, you can thin it with decil for practicing and then run all super-dri if you have a show.