Just noticed ESS are doing a vortech based S/C for the z4 now. I have emaild asking lots of questions....... I hope there replies are not what i want to hear... Otherwise my credit card will be taking a hammering!!!
http://www.esstuning.com/product_images/t/432/DSC_0087_%28Large%29__38996_zoom.JPG
http://www.esstuning.com/product_images/t/432/DSC_0087_%28Large%29__38996_zoom.JPG