This is from a magazine article on "dynojet" dynos.

SAE j1349 correction:
29.23 in/hg.
77 degree temp
0 percent humidity

Standard correction:
29.92 in/hg.
68 degree temp
0 percent humidity

What this all means is that "Standard" will give you 2.6 percent better numbers (very popular for the import crowd). The example the magazine gave was a Vette making 412 (SAE corrected hp). With the Standard correction it made 423. All that you will have to do is multiply your "Standard rwhp" by .974 This should equal SAE (the one everyone uses). Up here in the great white North (Washington) the temps are in the 40-50 degree area, along with 29.9-30 in/hg. So, our numbers are actually corrected down from what it made at the rear. Usually, 96-97 percent of actual posted numbers. If you dyno when it's a hotter temp or higher altitudes the numbers will usually correct up to equal the desired temp, humidity and pressure of the correction factor.