I'm tending to agree with Clubmyke.. Though, as I said before, if I had to do it again, I'd do it exactly the same. Plus I didn't like my neighbors anyway --(hours of tuning in my driveway)-- now they don't like me much either.
Perhaps reviewing some of Duane's suggestions a little closer. Bi-Amplification. I did this in my setup because I didn't want to take on building a x-over. It worked quite well. I used a Phoenix Gold electronic low-level cross-over that cost $22 of e-bay. I could change the x-over point on both the high & lows by swapping out a $.20 resister network. (I can give you a parts list) Plus it had 180 degree phase adjustment for the lows, Mixed mono/Stereo switch. Then I used a graphic EQ to take the "ear-crushing" edge out of the Compression Drivers. I could also power down either amp to determine where the SPL is at on either the horns or the mid-bass.
I've been hesitent to suggest any drivers as my experience base in drivers is very low. I don't want to suggest something and have you waste your money. I can share an experience though. Duane made a reference that the quality drivers don't have a big impact at 80' and 25mph. I agree with this too. Now I'll disbark from Duane's valid comments and continue with my opinion. In building my setup I used all JBL equipment. Why? because I thought to myself "I don't know much about this subject, I better go with good stuff because it'll hopefully cover up imperfections in my engineering." Well, at 80' the JBLs sound near the same as the Skylons. At 10 feet I like the sound of the JBLs better. Part of my problem was the weight of the JBLs, my compression drivers weigh 15lbs each. The Mid-Bass drivers weigh 20lbs each. On the flip side, the Mid-Bass drivers have a SPL of 100db, and the compression drivers are 110db. Pound for Pound the JBLs are louder than the Rubicon 450s. I can get the Rubis up there in SPL, but I have to push so much more power to them. I'm rambling, The JBL drivers that I used are IMO far higher quality than the drivers in the Rubicons. Though at 80' the only thing that matters is SPL. And it's hard to get anything below 500-700hz back to the rider. The pre-built stuff (NVS, Wetsounds) is going to get that frequency range back there much better.
If I could suggest one thing, I'd try going with three 8" mid-bass and one compression driver. http://bierbower.net/diytower/Docs/DIY HLCD Tower Speakers.doc
This is based off NVS's orginal design
Duane's orginal DIY post is around here in the archive sections. It maybe worth searching for it and reading it.
(Message edited by yosquire on October 20, 2006)