I just purchased them 3 weeks ago. I have recently checked both waste gates and they both open under pressure but the driver side doesn't work under vacuum. The driver side has been replaced as of last night and we can build 20lbs of boost but it doesn't build until 4000rpm and doesn't feel like it hits as hard as my factory turbos at 17lbs. I thought it might have been the AMS high flow manifolds not building as much pressure as the smaller stock manifolds.