A cheap one I bought a while back for an 89 had the outlet pipes 5mm too close to each other, so didn't fit through the holes in the casing. What I ended up doing was filing the holes out untill it did fit, welded 2 large penny washer over the now elongated holes and drilling those to the correct size. So in all 2 days work for something that should have just dropped in. I didn't have to weld washers over the holes etc, but did because I don't want air to leak out and bypass the matrix.
other than that the matrix been fine.
Dont be so dramatic, the one i bought and Maccers above, are the same , took 3min with a round file no big deal and no large gaps











