When you're in one, the sound (or lack of) isn't quite the problem it appears it will be. Sure, I'd rather hear combustion but the feeling of being pushed along by air is thoroughly addictive!
If you like these old 911s there's an US based company called Singer which does retro Porsches based on 964 chassis. What they're doing is top notch handcrafted art. Here's a link to a gallery with some of their projects but be warned. Clicking it will make you a drooling wreck for the next couple of hours.