Ok... using what clarkin explained... the nested IF block at the bottom can be changed to...
IF CHARINDEX('m',@outStr,0) > 0 BEGIN
IF CHARINDEX('mm',@outStr,0) > 0 BEGIN
IF CHARINDEX('mmm',@outStr,0) > 0 BEGIN
IF CHARINDEX('mmmm',@outStr,0) > 0 BEGIN
SET @outStr = REPLACE(@outStr...