from what i've heard, a Coscast will hold more heat (dont ask me why, thats a story that goes overhere), and that the best head is a fixed KS.
benn... i have some HUGE news for you ;)
i picked up my new wheels for the mk1 astra yesterday, and the guy turned out the be a distribiter for Image wheels in his spare time.
he had a very nice set, 3 piece, with the bolts in the back (so no bolts are in sight)
afaik the can do that with any wheel the do, just ask for it.
so you get this look (he had these laying around, there porn)
http://www.imagewheels.co.uk/wheels/...dm_classic.jpg