Hmmm I'm not sure I follow the non compressible gas theory... if the engine is at idle it's passing x cfm of gas (exhaust) through it. You close the vanes, that same volume of gas is still coming in. Now as the engine picks up speed, obviously more gas will flow, linear pressure increase until the turbo starts to come on line, then it goes exponential increase. It's not like water where you close a ball valve and BANG, water hammer, and the pipe resonates. Well, let me say it this way, not at the pressure levels we're talking about here anyway. A couple hundred pounds or more? That's called an explosion... I HOPE we don't have that at the head end of our turbos!
So, what's the difference if I'm at 1200 rpm and hit it vs idle? Once the turbo is at its minimum effective speed, response is the same rate of increase, PSI per second. The driven unit is stainless steel, and the compressor wheel is aluminum. I've never heard of a turbo going boom without something hitting it, or loosing a bearing and the wheel hitting the housing... unless it's screwed from the factory cracked, out of balance, end play, etc...
If you have a vehicle with a stick, and you're pulling a good load from a stop, once the clutch is out, (which should take less than 3 sec) You're full into it, and then you come completely out of it to hit the next gear and you repeat. That is way harder service, and much greater pressure and rpm change than you'd have with an automatic.
Rolling into it gradually does give a smoother response, but it's still not answering why it takes 3 seconds in the first place. Granted I know I'm dragging almost 4 ton empty around, but still... We had a 97 PSD in a 13,000# ambulance, and when you hit it from a stop, it went, no questions asked.
As far as smoke goes. I never see any in daylight, so far anyway. It's at night from about 1/3 throttle up that I can see it behind me in the lights. Just wondering if that is normal or not.
