i know the guy is great at 2stroke theory port mapping and whatnot but your robbing peter to pay paul any benefit you have by using a spacer to get the openings @ BDC to come in is lost in the head clearance ,it only increases the squish clearance further for m the target number you should be shooting for and doesnt change the blowdown because it raises the transfers and the exhuast ,makes much more sense to do it right and simply lower the transfers ot match at BDC and set transfer exhaust heights accordingly for the given pipe ,to this day i dont understand how a household name like rick kermil(macdizzy) has ,would represnt such crude porting on the net like that