If you are looking for that blow off sound. this Turbosmart BOV works great. It did take sometime to find the right spring rating setting. But if you knew, Saabs do no like BOV. So i ended up using the plug. Which is nice. Once I installed the plug. I had to change my spring rating again.
One thing for Turbosmart. I would like to suggest including a small packets of the special grease to service the valve. For the price point it should be included.
Other wise great product made with quality.
I bought this dual port bov because 1.8t's like many other MAF cars don't like full atmospheric due to air metering. I put the valve in and only had to turn it about 1 turn tighter and it works great. This valve stays shut during idle and vacuum so throttle response and boost is much quicker. I highly recommend this valve for the money. The sound is more of a pshhhh than a loud shreak. I am very happy.