Since adding the LEFT JOIN to the query below, the count(*) has been returning some strange values, it seems to have added the total rows returned in the query to the 'level':
SELECT `n`.*, exp_channel_titles.*, round((`n`.`rgt` - `n`.`lft` - 1) / 2, 0) AS childs,
count(*) - 1 + (`n`.`lft` > 1) + 1 AS level,
((min(`p`.`rgt`) - `n`.`rgt` - (`n`.`lft` > 1)) / 2) > 0 AS lower,
(((`n`.`lft` - max(`p`.`lft`) > 1))) AS upper
FROM `exp_node_tree_6` `n`
LEFT JOIN `exp_channel_titles`
ON (`n`.`entry_id`=`exp_channel_titles`.`entry_id`),
`exp_node_tree_6` `p`,
`exp_node_tree_6`
WHERE `n`.`lft`
BETWEEN `p`.`lft`
AND `p`.`rgt`
AND ( `p`.`node_id` != `n`.`node_id` OR `n`.`lft` = 1 )
GROUP BY `n`.`node_id`
ORDER BY `n`.`lft`
I'm totally stumped... Thank you!