I hope you are kidding too, the shaft on a k03/4 is o small that any type of chatter can cause it to snap, unlike the shafts on cossies and the like they are massive in comparison
i love posts like these.. they do make me smile.. Im pretty sure the K series turbo's are too small to block off the pipes.. evo's cossies etc.. they have big compressors and can handle it.. wouldnt be so sure about the little KKK's tho.
i agree with jason, get the 007p, much better quality, the OEMs are prone to going wrong, either this or get a stronger spring.
I also like being told how to run a turbo which I build and supply on a daily basis.
I mean are you being serious when you say snapped shafts as a result of compressor stall? if it was some serious chatter or causing compressor surge (which are different things) it could cause more bearing wear.
The stall is caused when the throttle butterfly closes and forces the compressed air back through the IC piping, some of this air pressure will be discipated by the rubber expandable IC pipework and the rest will pass back into the comp housing of the turbo and push against the comp wheel which can be spinning at 130,000rpm, the result of the air being "chopped" up by the comp wheel will create the flutter hoise which we hear.
If you are running serious boost i.e. 2.0+ bar on a non competition vehicle then running some sort of BOV would take some strain off the turbos bearings but I mean 1-1.4 bar of boost snapping shafts your having a laugh!
I ran a Hybrid CT9 turbo on a heavily modified Starlet Turbo which I had previously running 270bhp/tonne at 1.4 bar without any BOV for over a year with no issues at all and this includes track work and a very heavy right foot.
The long and short of it is the amount of chatter you get by blocking up the pipe on the S3 it isnt going to cause any more wear on the bearings than is caused when the turbo spools from ~10,000rpm to ~120/130,000rpm in seconds.
The reason people run without a BOV is because you always get some boost leak when you are on part throttle and between gear changes the compressed air/boost is not wasted and vented instead if you change gear quick enough you still keep some pressurised air in the IC piping meaning you will come back on boost quicker.
I dont mean to sound ranty, but I dont like being told about a subject in that sort of manner when it is something I do and speak about on a day to day basis.