A flat spacer yielding the best overall gains, the Motordyne 5/16″ plenum spacer outperforms the competition while keeping your strut bar and engine cover in place. This stealth modification adds 11HP-13HP and is the simplest to install. All Motordyne melt proof plenum spacers come with quality parts, pre-attached gaskets and self sealing plenum internal supports for OEM reliability. (Due to Carb regulations this item is not sold/shipped to CA. – No International shipping)