I'm considering upgrading ECUs as I find the MS3 doesn't have enough sensor inputs to do what I want. Anyhow, I hate the location of under the drive's feet for many reasons, most of all is running wiring for sensors etc. I would like to relocate to the passenger airbag, but have yet to find anything online that says they've done this successfully. Hoping some of you all have some info on this before I butcher something. Thanks!

 

Fwiw, I have done this on my nb1.
I fitted a Haltech and also didn’t want it under the dash so made up a short patch harness that plugs into the factory ecu plugs and then to the ecu.
I then made a simple metal bracket to mount it where the passenger airbag used to be. Access via the front pad that used to be the airbag cover.

bit easier for me as mine is RHD so it’s a straight shot up from existing location but wouldn’t be much different for LHD, just a slightly longer patch harness, which is zero extra work just longer cables….

 

Bottom line, you can put it wherever you want it. You then need to make the wiring to suit.

If it is a new ecu, an unterminated flying lead kit would work for most locations. If it is relocation of an existing ecu (or you want to reuse the exiting wiring loom) the patch harness works if you are comfortable with the complication/risk of the additional m/f plug connectors.

 

Link G4x pnps fit in the factory case, using factory brackets, makes it much easier. You can buy an extension harness or two and wire them wherever you'd like, to add extra sensors/gauges.

Once installed, I have the tuning cable, 4-pin CAN DTM, and 6-pin sensor pigtail hanging out the case, and I never have to access it again. For me, a 3 foot extension harness is too big a hassle to route behind the dash. However, if that's the route you choose, check out boomslang's website. They have an extension harness, dunno how long it is.

 

I’m with curly on using DTM connectors with the Link PNPs and installing in the stock location with stock brackets. On first install I plug both expansion harnesses and the CAN harness with the DTM connectors and don’t have to touch the ECU again. Fits beautifully and adding or repining extra sensors later is easy and doesn’t aggravate my back. Otherwise you’ll have to make a patch harness to move the ECU wherever you decide and you’re only limited by your imagination at that point. Having the ECU on the passenger side, either in the airbag hole or by the evaporator works well with Haltech installs. My friend used some heavy duty (forget the actual term) velcros that will not come off unless you mean it, which makes for a straight forward and robust install without making a bracket.