Weird. My buddy had prosystems blow thru's, with the throttle shafts pressurized via fittings for that purpose.

Do you have any pics of pressurized throttle shafts .I'm just trying to picture in my little brain,what you are describing

Let me see if I can find one

I was told by both manufactures that the only coast guard approved method of a blow-through carb application was with a box and if you had a fire your insurance co would not cover .

john, just remember you dont need alot of carb or cfm for a blow-through set up..all you may need is a 650 cfm carb..the air is forcing the fuel out of the carb..to be honest call c&s and have them build you a arosol carb with progressive linkage..i always use a carb that all four barrels open at once so your getting a equal fuel charge through the transition..their is a few tricks that need to be done to the carb in a blow through system..just changing jets dont cut it..you also have to open op the passeges to tje power valves to feed the bigger jets..just have c7s build a carb..http://www.candsspecialties.com/abcmods.html

I now am running our own EFI with a hat, using megasquirt, our own harness and tune...

He said even with "sealed" throttle shafts they do blow out a small amount of fuel under boost...said they noticed it on the dyno...

with carb...

with EFI

does your megasquirt throttle body have a shaft for the throttle blade or blades because if so you still may have some fuel leakage under boost.the deal patric from pro systems sells for carb apps with a hat consists if modifying the carb and a plate under the carb.it is a really neat deal.