Right Guys, After many years and near success and the missus now believing i own a speaker shop! I have finally cracked it! Below is the setup and how it is wired, it by passes the BMW wiring, this was first cause of frustration, it also by passes the BMW tweeter location, second frustration, having managed to get full range punchy speakers i have done away with the mid pass filters third frustration, and finally on mk3 version of the sub enclosure, i have achieved OEM placement of a phenomenal subwoofer. The full range speakers came as a result of discussing with an audio guru on the T5 forum, who sent me a pair of 6.5" Hertz component speakers for the T5, they were awesome, so i tried them in the Z3, wow, unbelievable, as they did not fit OEM, i sought out the 5.25 versions and i was not disappointed, so i fitted a second pair in the rear, bass is excellent. I then turned my attention to the sub again, and finally nailed the dimensions that allowed full extension of the speaker, and now it all works perfectly, and the sound is as good if not better than the T5. So cost of set up now, not what i paid: Alpine IDA X311R Head Unit - £80 Alpine KTP 445 Inline Amplifier - £70 Fli Underground FU360.2 2 channel amplifier (For sub) - £50 Hertz Dieci DSK 130.3 - £80 x 2 sets (front and rear) Kicker CompRT 6.5" Sub woofer - £80 RCA Cables - £15 Speaker Wire - £20 MDF for sub enclosure - £15 £490 in total. If anyone is interested i will post the dimensions of the panels to make up the sub enclosure, but please note this is for the kicker sub only, as it is a shallow mount speaker, i could not find another sub of similar dimensions.