50mm seems to be a heck of a large BOV thats 2 inchs , just what do you think would happen is you did plum the bov to the down pipe , first what comes out of a bov ,,fuel and air , sounds like a good way to stoke the fire in the exh down pipe , sure throw the 02 sensor for a loop with the throddle plate close'd all the boost pressure from an open bov simply flows in a circurt out and back in the intercooler,, it maintains the air volume so when your back into the petal, the pressure is still built up and ready to go ,,the more times the air flows thru the intercooler the colder it gets