Re: SOA vs. national
Do a search in this BBS on "SOA" and you will get all the posts related to it. I think you will find that the pro's and con's about about equal. In your case, wanting more than 4" of lift dictates either an SOA or radical change like the Black Diamond ($$$$$) from Warn. Important thing to note, there is NOT a direct relationship between lift and articulation...i.e., more lift does not always mean more travel. With an SOA you are keeping your stock springs which means that you have about the same travel, your only 5-6" higher. With a spring lift, you get a little bit more travel but because of the design, the ride gets stiffer. Presently, I don't know of anyone that makes a spring lift over 4".
An SOA will give you the lift and ride you want, the only downside is the extra gear you need to prevent spring wrap and driveline vibration. (Side note here...buy the CV drive shaft...otherwise, you will never really get all the vibrations out without it...this applies to both SOA and spring lifts).
After you read all the old posts let us know what you decide.