sounds like you have the final system about sorted, although one decent resonator silencer usually does the trick for me, but then i do like a fair bit of volume!
the trouble with virtually all the manufacturers crossovers and those that are commercially available, is the hugely UN-equal length of the primary pipes, they differ massively, not good!
the main reason for that is because its about the only way not to have them dragging on the floor, to go round and round the sump like spaghetti,
keeps them off the manholes but rubbish from exhaust purposes!
Personally speaking, I don't like the ansa much, the CSC is almost a carbon copy of it in my opinion too, trying to cadge sales from the old Ansa reputation,
if you can get the primaries equal length, the secondaries close too, you can make a decent job of a crossover, but its tough, and much easier with dry sump set up, and sadly no-one does that off the shelf.