ive been thinking about fitting an evo vortex generator on my rear window, but can't make up my mind if I like them or not. but they can be had for ~$20 on ebay...
ive seen those. they look good from the side, but the back view isnt so hott. i guess its because it doesnt cover the entire window.
Something no biger than this https://www.ebay.com (commissions earned)
like that one doesnt go from end to end. its flat at the ends. and its almost too big. something like a sunroof spoiler. It wont look right w/o an oem spoiler, which i dont have n e way. im gonna get one of the "M3 lip spoilers" off ebay, and factory match it.