If you are going to go through the hassle of upgrading might as well get the 22k btu burner.

Last I read about someone doing this Bluestar would only ship RNB parts to BS dealers or RNB owners.

So you need to convince a dealer to buy for you

Or get a RNB serial number from a RNB in your area that is unregistered.

Or get a local owner of an RNB to order the parts.

If something has changed I am sure someone will correct me.

There are a couple of videos of a guy doing just this on youtube. Vid link below.

BTW The guy used to post here but I think he got banned. Maybe you could contact him through youtube though.

Here is a link that might be useful: Hotrod Bluestar