We have been working with Sierra Circuits for over...

We have been working with Sierra Circuits for over a decade and have had many PCBs manufactured by them. Our PCBs have generally been 6-12 layers with track width/spacing at times of 4 mils. These have generally been controlled dielectric. We have had excellent engineering support to remove data issues that could impact PCB assembly. They are competitively priced and the quality of PCB has been excellent.
Keep up the good work!