When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
its shims and pushrods. so i would guess it gives you shims to put the rockers at a better angle of attack (for the valve guides to last) and gives longer pushrods to make up for the distance. or you could call thunderracing i bet they know.