There is really no upgrade for the stock 2mm apex seal springs.
Those people running aftermarket 3mm apex seals that only originally
use one apex seal spring per apex seal can make a their own double
apex seal spring system.  You can shave down another set of long
apex seal springs so you can run a double apex seal spring system as
with the stock, three-piece, 2mm apex seals.  Greater spring
force translates to better apex sealing, especially for high boost/high
Questions?  Comments?  Send email to: