N54 BOV Line Upgrade For BMW 1M, 135i, 335i, E89 Z4, E60 535iThe ARM N54 BOV Line Upgrade will help your BOV open and close completely and quickly. The ARM N54 BOV Line Upgrade allows you to replace the standard 1 8" line with a 1 4" line, doubling the size to allow ample pressure. Upgrading the diameter of the vacuum line running to the BOV ensures proper BOV function. With a smaller 1 8" line you can experience surging or over boosting if the BOV is not activating properly. HIGHLIGHTS Allows for 1 4" Vacuum