do i need relay for door/trunk w/ ns 1074

Exactly the same, do whatever you find easiest.

I just came across some 4 pin relays that don't have the middle 87a pin. Will it do the same job if I wire it like this: 86 - 12v fused at 3amps 85 - RS trunk output diode stripe towards RS side 87 - Ground 30 - Vehicle trunk wire So in this case I would not need to cut the trunk wire as in the diagram I posted earlier, correct? You mentioned the way you showed earlier as better. Is there a reason for that or just preference. Thanks for the help so far!

It may be, normally I use the 5 pin when that feed is pos, it's just that the line back to the vehicle ECU might be sitting on pos, the 5 pin separates, the 4 pin doesn't so the 5 pin is inherently safer. For the price difference and remember I'm usually buying about 20+ at a time, I always buy 5 pin, more versatile.