This long-rod piston kit has been developed to increase reliability and power from the Duratec and L5 2.5L engines.  These engines come from the factory with a short 5.975" rod that has a tiny .787" wristpin diameter.  We've gone with a 6.136" (+4mm) H-beam rod, and shorter .980" compression height piston to reduce the stress on the rods and crank.  Most of the other options on the market are tailored around the OEM rod length with either a .787" or .827" wristpin because that's what is commercially available, not what's best.  They will tell you that you don't want to use a shorter piston because it requires an oil ring rail, but for 20 years the aftermarket has proven that there is no durability drawback.  The reason the OEM's don't use oil ring rails is because they are an added cost, and require a small amount of additional time during install (both of those cost less than £5/set, but over 100's of thousands of engines that adds up to millions of dollars saved by the OEM for not using them).