No need to be offended.
Quoting boost@RPM, once again, demonstrates a misunderstanding of "spool". You are conflating "boost threshold" (boost@RPM) and "turbo lag" which is purely a time in msec. or sec. to a given boost pressure on a load-step largely independent of RPM.
We don't have the benefit of the map of the actual S356V in question, but we do have an S300 57.1/84 mm comp wheel map that should be pretty close to make some comparisons. A smaller inducer will shift the surge and choke lines to the left slightly.
http://www.turbos.bwauto.com/files/pdf/dimensional_reference/airwerks/S300GX.pdf
Sure, you can certainly get 400 HP (~44 lb/min with good lambda). You can certainly run the sucker to 52 PSI boost (PR=4.6). You can certainly get X bar boost at some low RPM to show how good it "spools". But none of those points will fall anywhere near where a 1.9 8V PD TDI's aspiration curves lie that's not either in surge or poor efficiency (I peg this criteria at 70% minimum and I also defy anyone that can show me an 8V PD not dropping off significantly in power over 5000 RPM). Go ahead, plot the dots and prove me wrong.
I'll start with one operating point:
http://www.not2fast.com/turbo/gloss...=3&SFC=0.365&AFR=17.5&maxInjectorDutyCycle=85
Edit - quoting again:
This is likely operating in surge.
At 3000 RPM and 3 bar boost (PR=4) the mass flow is about 26 lb/min. The surge line @ PR=4 is at 33 lb/min, but I grant that a smaller trim compressor wheel will have the surge line further to the left, but it's implausible to be >20% less.
At least for this particular map where the surge line @ PR=4 is at 33 lb/min,
this coincides with the 4000 RPM operating point. So congratulations, you've got a ~1000 RPM-wide powerband from 4000-5000 RPM. Personally I'll take a smaller, well-matched turbo, sacrifice some dyno queen headlining HP and enjoy a very broad powerband where I operate in daily driving from as low as 2000-2500 RPM and measurably less turbo lag and not just boost threshold.
