GSC has two options for the 2JZ our Dual spring Titanium retainer set and this simple and easy to install Single Spring for use with Stock Retainer. If higher revs or prolonged periods of revving i.e. road race applications, our dual springs are more stable at higher rpms and can be reved to 10000rpms when used with a shimless bucket. The Dual Spring kit includes: a Full Set of Dual springs: 91@33.65mm with titanium retainers