You don't need any relays.
12v feed from battery
Ground to chassis
Trigger wire goes to FPDM (There are two wires people tap, one is key-on, one is a prime and stop. Purple/Green for key-on, I believe Yellow/Silver for stock operation)
One side of Hobbs Switch connects to the same terminal as...
Run some Torco/Lucas fuel addtive and a tune from your tuner where the KS can add an additional +2 degrees of timing for when you want a little extra oomph.
In general WOT in OD gears is bad news, and I'd say if you don't cook up the smaller set of clutches, you may put your motor at risk. I'd consider taller rear tires as a stop gap here if you don't want to go down in rear gear ratio.
Take a datalog and see if it's actually flaring, or if it's commanding first gear for a brief moment instead of fourth. There's a TSB for this related to the leadframe.
Have used the HF bar a few times, works fine. Only issue I can complain about at all is the paint chipping on the bar where the washer/hooks are as you lift against the motor.
Being able to raise and lower the engine is nice when doing headers, gives you more angles to get to different bolts.
Don't use the O2 extensions. Once you peel back the tape and loom there's only one wire that has to be extended, it's the purple wire. I used a high quality crimp here.
Dustin/CPR supplies pushlok style hose that works there. If you prefer to move to a steel braided line, you will need a different drain connect for the turbo housing.
Here's a short order of operations that help you not go back and forth removing to reinstall pieces in order.
0. Install headers
1. Install K-Member
2. Install turbo support
3. Install crossover pipe
4. Install down pipe, leave hanging
5. Install turbo
6. Install waste gate
Also ditch the...
Well you already know that dynojet numbers will be higher, what you won't be able to measure is any gains from the work you performed going to a different dyno.