my advise is to replace the tweeters with the 88 cent specials. They have excellent response from 6khz up to 20 khz and will save you some money. Not to mention, they are tiny. (i believe they are made by audax, which will explain their good performance). With them, I would probably do a 6-8khz crossover point. I will get back with on the slope and crossover type.
