Found a really good source of info regarding set up from VP Electricity, granted its from a 1 series but packed full of great info on what not to do with audio, but if you do it here's how to sort it
Anyway for anyone interested
Linky Here
I was toying with the idea of some Dynaudio Esotec MW 172 8" under seats and was worried about mounting depth, hence i stumbled across the above post and it can be done, so i'm happy i have more options than SWS or Jenhert