I'm sure it won't be this, but it might be worth mentioning. The plastic cowling that covers the windscreen wiper mechanism can be loose if it's ever been taken off to do the windscreen mount rattle fix. I've just been round all the wheel arch liners today, securing them because I've had a small plasticy noise from the passenger side for months. I checked the engine bay and the Black cowling has quite a bit of play because the plastic fir tree screws don't torque up. I've packed it with a bit of inner tube until I get some fresh screw plugs. I've not test driven it yet, so not sure if it is the culprit.
The other thing I've had a go at today is the panel below the upper seatbelt pivot. Thought I'd sorted a knocking from the seatbelt hoop a while ago, but the lower panel still wanted to push in and out too freely so I ended up pulling the door seal out and prising the trim off. Hopefully I'll never have to take it off again, because I put loads of silicone on the fixings and the panel is now wedged with wood between the seat and panel until it goes off. Not sure if it's cured the knocking, but it is a decent strength knock I've had since buying the car, I can imagine if it's on the passenger side, it could sound like it's coming from the suspension. Worth checking it off the list.
GT 3.2 V6 - Q2, KONI FSD & EIBACH PROKIT, GTA REMAP, MICHELLIN PS3's, BMC CDA
159 SW 2.4JTDM TI - ALFATUNED, WIZARD BACK BOXES, KW V3 COILOVERS, NOKIAN WR A3/MICHELLIN PS3, PCA DYNAMICS ALIGNMENT.