If you can get your hands on a pair of OEM RAAL tweeters, they're worth every penny. More so if you're working with a small mid and have a highish crossover point, but can be used low too, but not for the faint of heart.
Who should I start talking to get a pair of OEM RAAL? :D
Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone.