You ran on a track that is fast and no one else can duplicate your fast times at any other track. Another guy even ran at your track and ran very fast. People on the net say that track is downhill.
Either way the 370z is a 13 sec car stock, and the 350z with the de engine is a 14 sec car stock. The hr is a upper 13 to low 14 stock mostly. I also ran a friend with a 350z hr Nismo with a few bolt ons and would slowly edge him every time we ran and I am only stage 1 and intake.
My Titan ran 15.1 in 4x4 mode and it was a Pro4x 2010 model. An Armada running faster, not possible, so that proves that track has some interesting things to have faster times.
The HR runs very close with the 370Z, not upper 13's.
I have run my Z's in 5 different states at many different tracks, the results have all been close, except at Atlanta Dragway, where the track is known to be notoriously slow. There I ran the HR in 100 degree heat, and it still managed a 13.5. Ofcourse my best times were in cool weather.
Our old Armada spun off the line, and ran back to back 14.9's during upper 40 degree weather. It ran low 15's in 90-100 degree heat another time. I only ran the big SUV a couple of times, for fun, while my Z was cooling off.
Here are the tracks I normally run at, and comparisons with other tracks:
Alabama International Dragway (Kind of like our Cecil down here, but not quite as fast) The track does drop off right after the finish line, hence some people's comments, but it is fairly level until then, but bumpy. My stock 07 HR ran 13.1's(Traps 107-109), stock 04 350Z ran 13.6(With bolt ons it ran and DR's, 13.2)
MGMP (Average speed and times) My stock HR ran 13.1's(Traps 107-108), stock 04 350Z ran 13.7, with bolt ons 13.2.
SGMP (Average speed and times) My stock HR ran 13.2 almost brand new(traps 107) (still green) 04 350Z ran 13.2's with bolt ons and DR's.
Silver Dollar Raceway (Average speed and times) My stock HR ran a 13.1 best(Traps of 106-107), my bolt on 04 350Z ran a 13.01 best on DR's.
South Carolina Dragway (House of Hook, known for grip but lower traps due to slight uphill climb at the end) My stock HR ran 13.1's with oustanding grip, but lower traps of 105-106.
Atlanta Dragway (Known to be one of the higher and slowest tracks in the SE) 13.5 during 100 degree weather with traps of 104-105 best.
If you live on the east coast, most tracks will fit in this group somewhere, when it comes to comparable times
Atlanta Dragway (Great facility, but a slow track for street cars and rarely prepped well for test and tune) It's only 25 minutes from my driveway though, located near the foothills of the mountains.
The other guy who trapped 109 in his stock HR Z ran at two tracks on the east coast. There have also been others running 13.1's at tracks all over, as posted at my350Z.com. Obviously, if you run at higher elevation tracks, you will not duplicate these times.
Here is our then loaded down family SUV (05 Armada) at Alabama International Dragway, while my then 2004 Z took a break. I had bet I could run a very high 14 due to the cool weather. Ran back to back 14.9's. I could have worked it down a tenth or two, but I was there to race my Z, not our family hauler. Some non driving SRT4 owner, who couldn't launch very well, even backed out of a race, after running traction limited low 15's, because he couldn't launch or shift well. I know his car should have been good for a low to mid 14 stock, with better driving.
http://www.youtube.com/watch?v=lkt7z-QFk4Q