Does not have to be an additional stage just one of the stages, whose time still contributes to the overall time, is identified as the "Power Stage", and then additional points allocated to the times set on that particular stage. So no extra running time just a bit of sorting the spreadsheet when the results are done. Also there could be a running board of top 3 times per class just to give people an incentive to push that bit more!
Happy to have it on the Tucker's Peril stage at Oxford
Matt