I am running the Rock n Roll Seattle Marathon next Saturday. This is my fourth marathon but the first that I have actually completed a full training schedule. I peeked at 55 miles per week and completed a 20 mile training run in 2:42 (8:08 pace). I felt good at the end of at run but am nervous about trying to go 10 seconds a mile faster and 6 miles further.  I want to target 3:30, but am scared that I will fall apart in the last 5-6 miles.   The pace calculators say that 3:30 is reasonable, but I don't know wether to trust them.  Anyone have an opinion about whether 3:30 is a reasonable goal?  I have been running for about 2 years and slowly built to the 50 mile a week load I have had this last training cycle.  I have been injury free this time.  Not sure what other info would help, but I will provide any answers anyone generous enou to think about this would like to have.  Thanks very much.