Curiosity just got the better of me, I just rigged up the old matrix under the bonnet instead of in the car, done the pressure test up to 13psi which exposed a weep along the plastic moulding of the matrix. Not content, I increased the pressure to about 16/17psi and the weep suddenly burst in spectacular style. Certainly would have made a mess in the car.
In a fit of rage earlier I posted the car in the for sale section, it still stands unless in the meantime i can find the right matrix, these patten parts just dont seem to be the same, too small, pipes dont fit etc etc....
Edit; How much would a new matrix cost from VX with a trade discount, might be my only option being as i cant post a wanted add.