How many Perrys are there out there , Id assume it'd have to be the same outfit. But thats only a guess .
On the Como 51 or was it the ST 60 3 window , the front of the two slots about on the baffle , the rear 1/2 open behind the baffle . thereabouts .
' They ' are two vertical slots approximate same timing as intake . Ea Side , NOT tangental - Angled substantially toward the bypass .
The ' Vane ' between the two slots thus also anglked same .
Yea , Clear unscavenged gas , but also the action rearwards reducing the typical 2 stroke waste comparable to over high valve timing overlap on a 4 stroke .
Which is why enhanced pipes have a strong effect . The PDP not neccesarilly being tooned pipe relevant . More a combustion cycle enhancement .