Rick 12v CTD

IP Question: Apart from the fuel pin, afc foot grind or removing the foot (which disables afc control) and the fuel screw what else can be done to the IP to increase flow/power? Anything that is common? Apart from messing with timing of course.

And fuel delivery question: I plan to run a second gen high pressure lift pump with a regulator. Can I T the return line for the regulator into the IP return line to the tank? Rather than run another line back to the tank

TRENDZ

I would suggest not using the second gen lift pump. I have one in my truck with a mallory regulator. The "return to tank" line on my truck was replaced with a new free flowing 3/8" line. It is "T" in as you mention. I also have a 1/2" supply line to the pump.
The problem I have, is at idle. The fuel pressure is very erratic. the pump seems to outflow what the regulator can dump. I have a pressure gauge in the supply to the injection pump, and it bounces rapidly between 5 and 15 psi at the regulator's minimum setting.
Although the fuel supply is enough to easily support my needs, it causes an uneven idle quality. The case pressure inside the injection pump controls injection timing, so every time the pump pulses, timing changes. It makes the idle "lope''.

Rick 12v CTD

you'll get a pulse regardless whether that be a low pressure pump or a diaphram pump too. Do you have a fuel snubber on your gauge? I'm not worried about a lope.

I currently run a low pressure lift pump and already have a high pressure pump from my ppump motor. If I don't like it or if pressures are too high I'll just put the low pressure lift pump back on.