This is my rough guide on how to be tight with your Jaguar build at the expense of future reliability.
- Leave out all rail clamp diodes for analogue inputs
- Leave out all LEDs, blocking diodes, and current limit resistors for them
- Use only one regulator and bridge the two power supply sections
- Leave out and bridge over the isolator chip
- Leave out the 5V clamp setup as without the rail clamp diodes, it's not needed
- Leave out the 5V rail thermal fuses, and bridge their locations
- Use an external map sensor for free from junk car, and don't install SMD sensors
- Leave off the MOV and bridge the reverse bias diode locations
- Don't install the MAT or MAF ADC sections at all
- Only install the drivers you need, for example, leave out 4 of the DPAK FETs, 2 of the SOT223 FETs, and one of the FET driver ICs, and all associated resistors, for a 4 cyl seq + wasted setup
But it WILL be cheap, which is necessary for some people.
Fred.