I have a couple of turbo questions.

I watch turbo cars at the track spool up at the starting line then when the launch it seems like the the engine shuts down, why is that?

Can you use a 88mm exducer compressor inside a frame design for 106mm?

What's the difference in sound from a small turbo to a large turbo?

 

It is likely what is known as a two-step revlimiter. By limiting the RPM at launch, one can't just blow the tires loose like an idiot. But, it also cuts the ignition which will send unburned air-fuel charges into the header; ultimately, this adds heat to the turbine and, effectively, spools it. This is the reason why you can mash the pedal on a turbo car — and keep it in a high gear — and have it spool up while the RPM changes very little (load responsive would be the effectual term).

No, you cannot put an 88mm compressor wheel in a cover designed for a 106mm wheel.

I think a big turbo making big boost sounds more menacing then a smaller turbo making big boost, but you should reserve judgment.