hey mate, thanks for resurrecting my thread :P in the end i put my tweeters in the air vent holes, in the bracket supplied with the speakers that let me swivel them towards the listener... i love where they are - sound is good, and my tweeters are big enough to fill that whole vent so it looks like its meant to be there... if you want a pic let me know.. i'll have to go take one.. i'd suggest if your tweeters fit nicely in those holes, put them in there... ive never used those vents - they are for demisting the side windows... i find that if you stick your windscreen demister on full ball the air still manages to reach the windows so they clear up fast too...