1 needed per car The price of these mounts equal OE replacements and have significant performance and reliabilty increases. 25% stiffer STREETDENSITY Mounts are solid rubber mounts with a 50 durometer, about 10% stiffer than stock, this means they still ride smooth and quiet but provide a marked improvement in drivetrain dampening over stock mounts. Livable street performance with serious sport intentions. Note, since there are no voids or air pockets in these mounts, even though the rubber is only 10% stiffer, the resulting reduction in drivetrain movement is actually 25% stiffer. 90% stiffer TRACKDENSITY Mounts are also solid rubber mounts, but with an 80 durometer approx 90% stiffer than stock, these are solid for all practical purposes and result in ZERO drivetrain movement. Vibrations from the engine are noticeably increased but not horrible. Definitely not smooth and quiet like stock mounts, but in return you get a completely locked down drivetrain with NO slop or deflection. These are perfect for the street/track enthusiast who doesn't mind a marked increase in vibration from the drivetrain. NOTE, THIS IS NOT AN OE MOUNT, OR AN RS4 MOUNT, AND ARE NOT AVAILABLE FROM ANY OTHER SOURCE - These are built by an OE supplier to 034Motorsport specifications. OE style gray rubber dust covers are included with each mount. Tech note: For a daily driver rig, we like to combine street density motor mounts with track density tranny mounts for a good mix of daily comfort and track-day readiness.