The DP 330 has lots of room for the smoke tank so keep it as close to the CG as poss. My personal prefferance for smoke systems in large planes are the kind with a pump and regulator. The regulator makes it easier to adjust the volume of oil for max smoke. The most common mistake is to pass too much oil. I've never tried the candle parifin that John reffered too but it sounds like a good idea. The bennett systems are ok and can be made to work well. the Gas/Atf Jsonin uses works well but its very messy, I use what ever stuff the hobby store has on the shelf.