I had the procal tune installed on my 2013 GT 6M today at a local dealership. So far, it's fantastic. I've run a few pulls from 0 to 80 and it just flat out goes. The low end torque increase really is impressive. I don't hear any unusual sounds or pinging, however I did notice the "clunk" that 5LITER_MUENSTER mentioned, but it's nothing I haven't felt in other cars that have fast RPM drops/engine braking. For me it happens more in 4th, but I was able to duplicate it on a downhill slope in 6th by gently tapping on the gas and releasing. It basically feels like my old 93 GT 5M -- the drive train was just a little "loose" feeling if you goosed the accelerator and let off under the right conditions.
So what would this "pinging" sound like in-car? Obviously the name implies it sounds like "ping", but I'm curious so I can listen out for it.
Black 2013 GT Premium | Track Package | Recaros | GT500's | JBA H-Pipe | Borla Over-Axles | OEM GT500 Spoiler | Koni Yellows | Steeda CAI/Tune | Steeda Ultralite Springs | Steeda Adjustable UCA/PHB | Steeda Billet LCAs | MGW | Forgestar F14's