AST makes high end 1/2/3 way monotube struts and shocks for most Asian, European and Domestic built automobiles. As with other high end shock makers, AST focuses on coilover style struts and threaded body shocks, and doesn't have a line of shocks made for SCCA Stock class racers - where the OEM style springs have to always be used. This prevents many Stock class racers from having good options for high end shocks - and the rules allow for two way, remote reservoir monotubes.
Vorshlag has the solution... custom lower spring perches made for OEM style spring ends and diameters:
BMW E90 3 series setup for FStock
Perches for 05-07 Subaru STI
AST 4200/5200 setup for 08+ Subaru STI
Vorshlag has been hand-making lower perches for a number of models for use with the OEM springs, as shown above. This has allowed customers with a number of cars to run AST 4200 or 5200 shocks in stock class including Subarus, EVOs, and BMWs. Shown below are our latest CNC perches for use on Mazda MX5s and RX8s.
This new CNC aluminum lower perch has a provision for a set screw to lock the perch at the OEM height. If an AST customer uses these with the stock springs but later wants to move to another class that allows a true coilover spring, the normal AST threaded lower perch can be substituted and 60mm or 2.5" ID springs can then be used.