ARCs Pro Series Billet Rod for the Subaru EX21 is 3.595" and it was designed to be a OEM stock replacement rod if used with the stock piston.
Pro Series Rods are CNC machined from aircraft grade 7075 T-651 aluminum. The Pro Series Rods have been tested to an average of 12,500 RPM and are the lightest available. Key features include an oil groove in the crank bore that is fed through a channel in the dipper and an oil groove in the wrist pin bore. These grooves provide a reservoir of oil that continuously lubricates the crank and wrist pin