Car runs great at that elevation actually. The first few times I ran it to Tahoe after installing the AF/R gauge years ago I was kinda surprised it didn't change more actually. Idle RPM slows a bit, but my base idle is set at close to 4k feet elevation now so it's not as big a change as it used to be. I run the primaries on my 750 DP a smidge on the lean side of max power for commuting anyway, so at cruise it was fine. The cam and porting all come in above 3k rpm so that's mostly on the secondaries. I mean, if I was going to race or dyno it at that elevation I'm sure I'd have to retune it, but just driving around was a piece of cake.
It had everything I needed and then some, I had left over connectors, wire, etc. I actually made a new harness for my Dakota Digital fan controller all out of stuff I had leftover in the kit. And I still have a bunch of extra circuits in case I go fuel injection and add an electric fuel pump or other accessories. Definitely not cheap, especially if you buy their crimpers (which I did), but in the long run I think it's worth it. I'll probably order one for my Challenger too when I get to that point with it, it's SO much easier to deal with than the original harness.