Both the BD and the Diamond Eye are easy to install. The stock is more of a pain to get off because of the heat shield and stuff. take the dipstick off the bolt its on - should be fine with it down in the trans though.
Ratching 10mm wrench is recommended and getting the stock off the turbo aint bad, just loosen the clamp, pry it away to get it to pop loose on all 3 sections. If need be lift on the exhaust end to twist the turbo end and break it loose. PCV re-route is simple and keeps all the oil out of your turbo and intercooler. BD manifold isn't too hard either - inner fender, steering shaft (hold wheel with tape or bungee),
SEATBELT WORKS GOOD and then bolts. Spray them with good penetrating oil a day before, then while they are warm after you get to where you are installing it, then right before you break them loose and they should be easy. Gauges are also easy and I have my DiPricol gauges wired to my factory dimmer wire so they dim with the dash - but they also come with dimmers on the wiring kit that you set before you install them.