Of anything out there currently -- for this purpose... the Peerless -- the LPG won't go low enough to pair with the L18 if you ask me... You would need a more expensive tweeter or a large format tweeter for the L18 (or Dayton RS) to work... Not to mention they are a little less forgiving on the setup if you are unsure to say the least...
So I say the peerless... Will be a fun tweaking process...
I'm going to have to agree here
there are only 2 drivers in 6.5" size that will mate to the point you're looking for... at least that I can think of off the top of my head... and that's the Adire Extremis and PHL midbass/midrange (1220 I believe)
neither of them are cheap... but they both would sound great... I would probably give the edge to the PHL here for that top end
you will need to have some kind of lower xover point with just about any other driver out there... if you want to keep ultra high SQ (i'm talking
a larger tweeter like the RS are made to play lower but at the cost of size... definite downside
good luck
