Maybe you need to get Robert to Make a "Binaural Recording" for you.
Find an old shop dummy, drill a hole where the ears are and embed a cheap microphone in each hole.
Send this to Robert and get him to drive around with it in the passenger seat, while recording the noise to a laptop.
Maybe for a more accurate recording of the noise from the driver's seat, Robert will need to drive around with the dummy on his lap, but I'm sure this is a minor inconvenience.

Do the same thing in your own RAV and compare.
You know it makes sense.

................in fact, if you like the noise, just stick to playing back Robert's recording in your own RAV through headphones. You'll get the same effect as the twin exhaust, it's much cheaper and you won't be able to here any annoying passengers.
Engineers - Can do for tuppence what anybody else can do for £1. Can you see why I are supposed to be one?