Is if you have larger turbos than stock and the stock recerculation valves won't hold the boost. Stock recerc. valves in good shape seem to be able to hold up to about 21 lbs. of boost before they start leaking to the point were you cannot make any more boost. That's not to say that they are not leaking some before that point. With that said however, it seems that mine are holding only to about 17 lbs. I will be put on BOV's very shortly.
Fred 95 300TT SGP Stage..Who knows..lol Dynoed 539.4 RWHP, 481.2 Lbs. Torque Pump Gas @ 17 Lbs. of Boost NO NOS!!