Nearly all agree that dual valve springs are needed for engines revving over 7000 rpm. We recommend these for all track cars and any M20’s using high lift cams.
These double valve springs are 35% stiffer than stock.
Note: This kit will ONLY work in conjunction with itself. These springs will ONLY work with these retainers/cups and vice versa. It will work with stock valve stem sizes and collets.
Kit comes with:
– X12 Chromoly Upper Spring Retainers
– X12 Dual Valve Springs
– X12 Chromoly Lower Spring Cups