the reason why the maf doesn't affect stalling when blowing off on the stock msp setup is because the stock msp setup recirculates...if you run a VTA setup with the maf on the inlet pipe you WILL stall coming out of boost straight down to idle, period
if you place the maf on the pressure side before the bov and VTA, you will stall coming out of boost straight down to idle...period
if you place the maf on the pressure side after the bov and VTA, you will not stall coming out of boost straight down to idle
this is from personal experience with several bovs and keeping the maf both in the stock location, before the bov on the pressure side, and after...as well as using several different intercooling piping routes, and with oem msp piping....using a second gen HKS SSQV, a GReddy, a bosch bypass valve, and a TurboXS VTA only bov...you will stall coming out of boost straight down to idle if you vent to atmosphere any air after the MAF has read how much air is flowing into the motor because the motor will choke itself out with fuel as it is compensating for X amount of airflow and only actually receiving a portion of that amount of airflow
on the note of bov placement to determine whether or not the coldpipe or hotpipe is ideal...it doesn't matter if you are wasting cold air or not because the only use of colder/denser air is for performance gains, which is not an issue when you are releasing pressure in the pipes (i.e. not on the throttle)
what IS an issue is how quickly you are able to relieve pressure in the pipes to avoid compressor surge...now on our setup at under 10psi it doesn't really make any difference which pipe you are running your bov on, however if you have the choice between the two the rule of thumb is to place your bov on the coldpipe...this being that colder air is denser air, and as such you are able to relieve pressure in the intercooler piping faster with denser air...but again, this isn't really going to make any difference at such a small about of CFM of airflow that a t25 produces
