I've been running the R1 Wurks 200c 7600mah pack with good results in GT12 (USGT motor on foam tires. 4 to 6 minute runs). We're going to start running 17.5 LMP here soon so will see how it performs there. Not sure if we will run 6 minute heats and mains or 8 minutes. I do have some older EAM 130c 8500mah packs that over a year later still have IR numbers 1.1 to 1.2 on the iCharger.