www.bimmer.org or roadfly.com has the most hits but your post will get push back pretty quick. www.e46fanatics.com has some nice guys. i met a few of them at the 3/23 meet. they're usually very helpful and if u post, there's always someone replying.
the redline is 8k but i would not go that far cuz i know the peak power and tq is not that high. plus we all heard about them engines blowing up. other then that they're awsome. i would suggest you take the bmw car control clinic. its very helpful if you have a very powerful car like M3.