Today my '01 HO 6spd with 113,594 miles passed with 7. 3% opacity reading out of a max limit of 40. 0%. The test type, according to the print out, was a "MSA (Diesel Snap)" and shows the number of "snaps" as 3. Also, the print out says "untestable on dyno". I watched (and listened!) as the guy revved the truck way up 3 times pausing after each time. For comparison, my last test 2 years ago at 80,005 miles, at another shop, it got a "LMD(Diesel Loaded)" test and showed 0% with an opacity limit of 20. 0%. That test was done on a dyno (I'm pretty sure!) and that print out also lists "rpm"1810, "horsepower" 15. 6 and "equiv test wt" 3875. Oh well, as I sit behind the wheel and drive, the truck feels and sounds the same to me as it always did. If the driver's door doesn't rust thru I still may be driving it in another 2 years when the next test is due! Next up,... ... ..... new tires.