Good point RedAndy3575. I also do most servicing on my two P38's myself, but still get a workshop to look over them at least once a year to see what I have missed.

I had a 1995 4.6 HSE (GEMS) and I maintain that my 1999 4.0 (Thor/Motronic) has as much grunt. My/wifey's 2000 4.6 HSE (Thor/Motronic) is better again, although it is highway-biased and mine is bush-biased.

For diagnostics, I have both a FaultMate MSV-2 and a Nanocom Evo 2. If I was starting again, I would just get the Nanocom. Will cost you around $500 from blackbox-solutions.com

For the air springs, it is a personal choice but I like the Arnott Gen III air springs. Will cost you around $1000 for a set of four from arnottindustries.com

Other EAS stuff has been covered. No harm in doing the o-rings in the valve block and piston seal on the compressor every year or two... they are just another maintenance item.

Cheers, Paul.