GSC has two options for retainers you can either have Chro-Molly or Titanium do to the type of abuse a street cars valve train sees we suggest Chro-Molly and Ti for race car applications. The Chro-Molly will last just as long as the stock units that they will replace. Unlike Titanium these will not become brittle over time. They are only a few grams heavier than Titanium and will not affect performance. GSC Chro-Molly retainers are universal to use with either our single valve springs or our dual springs. The single valve springs do not require a new seat or different seals where as the duals will. A set of valve springs can be changed in a matter of 2 hours with the correct tools, and is the best insurance a car with upgraded cams can have. The single springs have been tested higher but we suggest a max rev limit of 8500rpms. If higher revs or prolonged periods of revving i.e. road race applications, we suggest going to our dual springs which is more stable at higher rpms and can be revved to 10500rpms. The Single Spring kit includes: Single springs 78@39.6 with either Titanium or Chro-Molly Retainer. *Beehive Spring Set* GSC Power-Division Beehive springs feature some of the most impressive manufacturing techniques in the industry. Our beehive spring uses an ovate wire which utilizes advanced material heat treatment methods for superior load loss capabilities. What this means to you is our spring has the highest level of spring load retention while still maintaining good fatigue threw out the life of the spring. The retainer side of the valve spring has a smaller diameter to greatly reduce coil spring surging and improve valve control even at extreme rpm levels. Only the best materials go into the GSC Power-Division Beehive valve spring. Each batch is scrutinized for tensile strength properties, ductility, inclusion content, and fatigue toughness. Each new design is tested to 9,000RPMS so you can rest assure that you have the best possible valve spring set available on the market. The GSC Beehive spring is a factory replacement and will use your stock OEM retainer and Valve Seat to ensure an easy install.