Thanks for the info ybturbo, just one other question which I hope you can help with. If I leave the non return valve in the inlet manifold and just connect the charcoal cannister purge pipe to this surely it won't be able to purge the fuel vapours when over 3000rpm due to the boost pressure closing the valve. With the curent setup it can purge into the breather if the non return valve is closed as it is T'd into both the breather and the inlet manifold.
I'm starting to think I would be better off just Ting the charcoal cannister purge pipe into the new breather somehow as then it can always purge the vapours no matter what the engine speed / boost pressure. Will this be okay?