You can only go so lean on a engine at the HSN and i personally would doubt they were running excessively lean on the top. A long final you'd want reliability instead of a increased risk of blowing a plug. Plus i don't think they looked that 'lean', you can never tell anyway by watching the videos by looking for smoke. A lean engine would bog anyways be it on the straight or exiting a turn. Seriously, don't go tuning by temp. . . . worst way to go ever. You'll knacker a engine trying to get that 'magical' temp reading of 250F in a 2*C weather conditions.