Well there have been quite a few setups where the turbo was first and quite a few where the blower was. Both setups can work. And some use a bypass once the turbo comes to life so the blower is not a restriction. The twin turbo blown duramax you talk of now just has a whipple and spray and no turbo. I made some progress got stuck for a few days trying to figure out how is was going to build the discharge elbow and looking thru my pile of parts found a Detroit 453 blower inlet that's going to work.
I would place the ducting and blower so that I wouldn't have to move much to let the stock charger feed through the intercooler then from intercooler to blower, then blower to manifold. Place a couple water injection nozzles in between blower and manifold and let the big dog eat. Would jump on boost. But still move no more air, but PR would be better, so more density maybe. Upping the turbo size would be the next step with the blower handling low rpm duty.
If you can't get up on a stock charger without help I'd look at something other than the induction system anyway.
The problem with smoke free 300hp IMO is the limit of the stock charger to make the 300hp without smoke, not for the stock charger to come up off idle making power. A blower of the size mentioned is barely capable of supplying the air the stock charger can, and with less efficiency, so I don't see the benefit.
Now, letting the blower pick the truck up off the bottom, and having a
larger turbo feed in up top I could see. That would augment the need for O2 to achieve 300hp without smoke.
Lastly, the injection nozzle size probably has more to do with this goal than anything in this thread.
Regardless, if you do get something driving around, it would provide some interesting tests.
On Edit:
The blower setups I've read about before with blower ahead of turbo have a knack of viewing a dyno like superman does Kryptonite. Oh it drives so awesome, blows the tires off, so badass.....
Yet anybody that drives or rides that's familiar with similarly turbo'd engines says meh.... Noses over... snappy and that's it. A decent compound setup will send your rods into next week at 1500rpm if low rpm power is your goal anyway. I've always had to pull power down low for engine longevity. Even my 550 with a single 38R has reduced fueling down low to keep things calm. In fact, it also has the larger 1.15 turbine housing. The last thing I need is more help down low. And it's a tow truck. Coincidentally it makes around 300hp. If I wanted to turn the map based fueling on it could be smoke free, but I like the simplicity of flat maps and as little trimming as possible, so it huffs smoke until it lights.
