A lot of people in America use them, because they come in pre-packaged upgrade kits from various companies
Theres a lot of positive feedback on american forums
what fuel pump and fpr are you using
also, what is your base fuel pressure at idle set to?
when i installed my sard fpr
base fuel pressure was set to 80psi at idle, so at full boost it was hitting around 100-105psi
wasn't running well at all