I am currently using the sealed gage sensors. 0.5 output V at 14.7 PSI. Its the one with the dotted lines. The part number is PX3AN1BH 150PSAAX H 7412.
This code:
float psi = (0.1832844575*sensorVoltage) - 18.75;
is supposed to be the same as y=mx+b. At least that's What I got when substituting the PSI with the range an analog input reads on the arduino 0 - 1023.