I have entered my details in the 737-800 FMC and noticed it let me climb at 275kts, but when it gets to FL350 it only travels at M0.600 (205kts) and descend at 264kts, is it a limit over the area from KLAX to KDEN, or is something wrong in the calculations.Other times it let me fly at M0.780, anywhere else such as KDEN to TJSJ..(so far)

Hi, I had a similar issue with clean installation on a new system. Although I was unable to determine the root cause of the issue I have spent some time to verify the differences between 737 and 747 .rte files. It seems there are few, but the only difference that really matters is the number of '0' lines for each waypoint.The 737 is having:21 consecutive zero lines in each enroute waypoint18 consecutive zero lines in each airport waypointThe 747 is having:22 consecutive zero lines in each enroute waypoint19 consecutive zero lines in each airport waypoint Knowing this any serious text editor can do the trick of search and replace on the .rte file to change 737 to 747 and the other way round.Hope it helps.Attached example is the 747 flight plan file for LKPR to EKCH manually changed to become 737 file for the same route.For reference my setup is FS9 with 737-800/900, 747-400 and 747-400F and all patches.