I want to wire in a fuel pressure sensor to s300 and i know there is 2 analog inputs and how to use those BUT...where the hell do i get the 5v supply for the sensor? Regulator?

 

Are you looking for where to buy an analog pressure sensor?

http://www.innovatemotorsports.com/x...cat=265&page=1
12v input 1-5volt linear output

Or are you looking for a 5volt power source (wire) to give power to the sensor?

What car/chassis are you putting this in?
You could tap into the VCC2 (5v sensor power source)
OBD1 = ECU pin D20 (YEL/WHT)
OBD2 = ECU pin D10 (YEL/BLU)

 

oh well if that one is only 10$ more than the one i was looking at then that is more convenient. PCS has a slew of sensors and transducers that are 5v input...