A buddy of mine recently did an automatic transmission swap with non-lockup torque converter and had his motor built for high boost and a little nitrous like mine. Before the swap and the engine build he had a 2.76" upper pulley only with intake, catless x-pipe, cat-back, and a tune and was seeing 14.5 pounds of boost. Now he has put on a 2# lower along with the 2.76" upper pulley and is only seeing 12-13 ppunds of boost when he should be seeing around 16-17 pounds. He has a single idler pulley. Could this problem be vacuum related, belt slip related or something else? Any and all advice would be helpful for him so please give your input guys. Thanks. All, take it easy.