The loom I made - for an Impreza - has connectors for:
Oil Pressure (mounted under alternator)
Oil Temperature (mounted above Cylinder 3)
Air Charge Temperature (mounted near throttle body) - see footnote.
Fuel Pressure (sensor replaced mechanical gauge of my FPR, on rear bulkhead).
The harness is professionally made and properly sleeved with high temperature fibreglass sleeving, using heatshrink at each joints, and proper mating connectors for the sensors, plus crimped pins for the Subaru ECU (or, alternatively, crimp pins for a GP ecu) and a power connector for an S6PnP (or wire ends for a GP).
Sensors are AEM 10 bar for pressure, and generic FAE sensors for air and oil temp. And I can include the M18-1/8NPT adapter for the oil temp blank above cylinder 3, and a braided extension hose/adapter for the oil pressure sensor that allows the oem pressure switch to be retained, as per most gauge installations, on Subarus at least.
Whilst the lengths I used on my prototype are optimised for a Scoob, it would be no problem to alter lengths to suit other vehicle, although I would need advice on the cable lengths.
A bundle of all 4 sensors and the loom would retail for around £250+VAT - the sensors and oil adapters can be bought elsewhere for about £170 all in: you can decide if an extra £80 is worth it to save yourself the hassle of having to do all the wiring yourself
May I ask people to reply to this if they think it is something they would interested in buying, and/or have any comments or suggestions? That way I can decide if it's something worth pursuing or not.
Lead time would be about 2-3 weeks from a decision to proceed.
(Footnote: once I finally receive prototypes, I will also be offering 82mm long silicone reducers/joiners with a moulded-in boss for the air charge temperature sensor. Two sizes initially (76-70mm, and 70-63mm) others can be made. These will sell for about £45+VAT)