I don't want to offend you in any way but in my opinion, you're wasting your time. I did the baffle mod, stack mod and moved the thermometer down to grate level. After a couple cooks with the mods, I decided I was done fighting it. I ordered and 22.5 WSM and couldn't be happier. I don't have a 150* temperature swing from one side of the grate to the other. I don't have to constantly babysit the fire. I have a lot more room, probably more than I'll ever use, and it takes up less room on my patio. This place has the 18" WSM for $239 shipped.
http://www.aimtofind.com/weber-18-5-inch-smokey-mountain-cooker-pn-721001-2010-model.html
It says the sale ends 6/11 but I think this is their normal price. It's always on sale. They just change the date every few days.
Like I said, I couldn't be happier with my 22.5, I'm sure the 18.5 is just as good. :thumb:
Bartstop