The 20hp with the Bren was also with the rpi scoop thing and an exhaust. I know ESS had some dyno run with the scoop and 20-22hp was seen, ESS chose the lower of the dyno runs for their hp posting. Just something to think about.
http://www.zpost.com/forums/showthre...t=ess+software
http://www.zpost.com/forums/showthre...t=ess+software