My Regal was shifting at 6200 RPM with a completely stock setup (only a 180 stat, short ram intake and DHP custom tune was done to the car at that time). Told the guy tunning I didn't want the RPM's raised, but he said he only raised them a little. Changed the harmonic balancer twice in a year cause of it. And when the guy I bought the GTP from ran a 13.3, he was running slicks and broke a ton of crap doing it. But still even with that, this Samson guy says Im at about low 13s@104.