Porous Metal Muffler with Adjustable Speed Control, 1/4 NPT, 1.45 Inch Long

You can tune it either way, honestly. The external adjustment screw gives you a range from fully closed all the way to full flow, so you've got real control over how much air passes through. Once you land on the right setting, the locknut holds it right there so vibration or bumps don't walk it out of position. It threads into a 1/4 NPT port, so if your line already has that fitting, it drops right in without any adapter business.