T1 never had strong bass. It was non-Dolby, Academy mono, which always lacked low end. To add bass is to alter the mix to something it never was. It was an 80s B movie, it should sound like an 80s B movie.

And changing the FX would be no different than George Lucasing it. (Speaking of which, you are going to unfix the fixes made in the DVD/BD transfers, right? I know there was a shot in the future war sequence of that Terminator infiltrating the bunker, which originally had him facing in the wrong direction compared to the wide shots...)