mine megasquirt is mounted under dash, to the passenger side, can see those couple leds and easy to connect lap top. relays etc are under the hood, not yet finally installed, but they are going at own aluminium box, now mine is like in a test sessio
my sds EM4f is under the dash on the driver side, must keep it out of the engine compartment, rubber mounted or some other way to isolate vibration is good too
I got a te72 with a 10pt roll cage thinking about msd and ecu ( Big Stuff) under passenger dash just gotta fabricate a plate for the electronic. also easy access and semi hidden, Aloha Mark