I've got a problem others may have had, but I'll post my issue. I have the Roush phase II SC dealer installed on a base '16 Mustang GT. It was part of the '$39,999' promotion a couple of years ago. It's an M6. 3.73 gears. I have several suspension upgrades and full length, long tube headers with X-pipe. I use MT drag radials. I have had it tuned at a local speed shop. Dyno numbers were about 600 to the wheels at 6800 RPM. 'Officially', this is the 727 HP package. I do have an SCT tuner. And, I have used it. The issue is that at about the 1100-1200 ft. mark, power is completely shut down. I adjusted max allowable RPM range thru the tuner to 7500, but it still shut down. The problem could be the 3.73s? In 4th gear I get to about 7200 RPM....around ~ 1100 ft. mark....and then power is pulled from the engine. I do have the advance-trac disabled when I run. So, the track nannies shouldn't be the issue. I'm thinking of setting max allowable RPM to 8,000 to see if that fixes the problem, but it could be something else? A sensor? intake temps? I tried just shifting into 5th gear, but I lose too much ET at that point on the track. I should have done more research on the tranny gear ratios. Knowing what I know now, I would have kept the stock 3.31s in it. I probably wouldn't have this problem if I had done that. However, that is where I'm at right now. Any advice would be welcome.