When considering Dyno numbers, in additon to what Reid stated you have to consider...
Manufacturing variables in the engine and tranny
Maintenance variables in the car done by the owner
Wheel/tire choice (weight)
Current state of tune (sort of a maintenance issue).
When I did my dyno, my car was spitting black carbon out the tailpiple like there was no tommrow, yet others who dyno'ed that day did not have that problem. Per the OBD-ii software, everything on the car was operating normally, and within spec, so we never did figure out why my car was spewing carbon. It was not running rich or lean, just sooty! (lol). I pulled a 110 that day bone stock.
Also. Type of Dyno, and the dyno's calibration matter. Dynojet claims that if you do a run anywhere in the USA on one of their Dynojets, you should get repeatable numbers within 1% after correcting for SAE. However, since some shops DO correct for SAE and some dont, and some dyno's have been caibrated recently, and some havent...etc...etc..etc... it just adds in more variables into the mix. In reality, I feel that a 10% correction factor across dyno's is more realistic. Unless you know the same cars were dyno'd the same day, on the same dyno, under the same conditions...go with 10%. If they were all done at one place, at one time, on one dyno...then go with the 1% reccomened by Dynojet.
From my observations, In general...Gen2's seem to dyno higher than Gen1's. Don't ask me why. Could be lower mileage on the newer gen2's vs the older gen1's????
One quick example of all of the above. At our recent so cal dyno day with the Nissan SE-R club of Los Angeles...the dyno we were using, the software on the dyno had not been updated, so we were informed that all runs under 200 Hp would be reported as 5 HP low. So my recorded 169/168 is actually a 174/173.
The First gen we had there with a MHP CAI, pulled a 120/118. That was actually a 125/123.
However, since they did NOT adjust the dyno sheets to reflect the 5 HP/Torque difference...I'm sticking with the 169/168. I can PROVE that. I can't prove the dyno shop told me to add 5!<img src=/images/forums/snitz/tongue.gif width=15 height=15 border=0>
<hr width=60% noshade size=5 align=left>Leave it to Random to Needlessly complicate things.