Rainbows are the best
i have the aluminium ones that are 400 quid, they are amazing, i had 5 sets of rainbows i aquired, all sold now, exept mine which im keeping and a set of 5.25 coax which i want 75 quid for..
another manufacturer worth lookin at is Focal, i have some of these too, much better than diamond and as good as Rainbow
and the Focal subs are amazing, got one of those in my car and it rocks!!
These are my Rainbows
http://car.rainbow-audio.de/products/introduction.php?lan=2&pro=1&lin=17