RE: F1 sound
If you have room for and can carry the extra weight, a powerfull amplifier and speakersystem, loud enough to drown out the Zen, with the batterries to power that system. you could use a soundsampler like the ones used in scale boats, to produce the sound you want, coupled with the position of the throttle, so when you throttle up, so does the soundsystem.
I can think of a number of reasons why this would not work satisfactury in a fast boat, mainly because of the extra weight involved; you'd have a boat at tug speed, sounding like a F1...
Anything smaller and lighter that wil fit in the boat will produce the F1 sound, but won't be able to drown out the Zen.
Maybe a headset, coupled to the mentioned system, so only you hear the F1 sound?
Regards, Jan.