Erik,

Do you have field restrictions and need something somewhat quiet or can you allow some noise and maybe get a better breathing engine? The Slimline pitts has worked well for me and can be purchased with smoke tap. I think Abellrc.com has some very good mufflers that allow for less restriction and are also smoke ready.

Some others you might look at are Whacker Engines and Bennett. There is a Bennett muffler on eBay with tapped for smoke right now. Whacker's eBay store is at http://stores.ebay.com/Wackerengines

Hope this helps...