Right, sorry to harp on about this but....................
I have a T-Piece with 4mm x 4mm x 2.5mm diameters. The vacuum hose on my car is 6mm so I am stuck.
I can't find a T-Piece that has 6mm x 6mm x 2.5mm so the only thing I can think of is to buy some 6mm to 4mm reducers and fit the T-Piece I have. So my question is, will the reduction in diameter of the vacuum hose have a detremental effect on the car?