I had never pressure tested them individually until now. After mounting the IC's and tightening down the t-bolts on the car, I boost leak tested the entire system and felt a small amount of air coming from the back face of the IC. Frustrated from fumbling with the t-bolts (I used 2.0" and prob should have used 2.25"), I left it alone. The leak now seems bigger and apparently is effecting my idle. I'm now trying to make my car boost-leak free before I run to the drag strip soon.
1990 Nissan 300ZXTT Stage III+ 11.96 e.t. 1.61 60ft on original stock turbos