what's the difference between PFR6G-11 and PFR5G-11? PFR5G-11 is for normal driving condition and PFR6G-11 is for harder driving. SO what's the draw back/advantage of having a PFR6G-11 over the PFR5G-11? I have a couple of mods so should I go with PFR6G-11? look at my sig for the mods I have and let me know which plugs should i get.