Per my post awhile back, i had Bob Crites upgrade the crossovers and install the titanium diaphragms in the tweeters and I was amazed at the difference. Cleaner, fuller sound. More extended highs and much more solid bass at least to my ears. I was actually on the verge of replacing them but now with this upgrade will probably keep them for another 10 years. I also had the same work done on the center channel ( CF- 20??, don't have in front of me) and same results. I live near Bob so had him do the work but it didn't appear overly difficult. Mainly removed one of the woofers to access the crossover and removed the tweeter to install the diaphragm. No opening the cabinet itself otherwise.