the exhaust as it stands is an 1800 zetec magnex, not specific for a turbo no boxes removed just rear and centre section so should be plenty of pressure

oil return i have jus done again with a 20mm pipe so thats plenty big enough, ie it matches the pipe out the turbo and made it a straight pipe, no bends etc.

the smoke has lessened a bit since i have done the oil return

cheers for ya help chaps!