deputydog:

Thanks for the info. The Bisson looks to me like it has a smaller box coming off the inlet. This could be a restriction as far as pressure goes, but it's hard to tell by the picture on the web site. As long as the Slimline has corrected the problem I will go with them. It's 'cake' to install a smoke nipple. Most all 50cc gassers and up are plenty hot enough to produce good smoke. I have smoke on my BME50 and the smoke fluid gets burned completely. No preheat. I'd say 95% of the time preheat only is necessary with a glow engine. Again, thanks and I wonder why the curled it in the first place? Maybe thought it looked better?

PS...The same reason in getting one is to not having to chop up the cowl so much...