what size vacuum hose for MAP option?

[Mk1Sport]

hi there. im new to these forums and ive just purchased my MJLJ ecu to fot to my Mk1 Escort. I've ordered it with the MAP option, and was just wondering what size fitting the ecu has for the vacuum hose (i'm guessing its 5/16?)
my motor is on twin 40's, and i am planning on collecting the hoses from the runners by using three t-intersections (one joining 1,2 another joining 3,4 and another joining those two together) and then running that hose through a fuel filter (to act like a balancing plenum) then into the ecu. does this sound right to everyone? i thought it works out nice and cheap this way...
anyway i need to know the fitting size as soon as possible because i'm on a tight schedule to get it running!

thanks for any help!

Regards,
Julian