i have just finished upgrading my jbl L26 with the Gravesen crossover upgrade, new acoustic damping/felt, etc.
The difference is stunning.
A simple recap would no dout have improved tnem, but all the upgrades have transformed tnem.

Now, i also have jbl 4312mk2 with the titanium tweeters.
Also wonderful.
Gravesen does not have an upgrade for tnese as far as i know.

Does anyone know of a crossover upgrade for these?

Although they sound excellent, the crossover is still quite simple,and i wonder just what might be acheived with a bettercrossover.