Originally Posted by Island_370

1 of 3 reasons......

It is a heartbreaker dyno
the correction factors are wrong on the dyno or (the most likely)

The dyno is at a shop that is going to sell you mods and then re-dyno. They want to get a low baseline number so that $1000 pulley gets you 25 hp and you will pay another $2000 for a high flow Kuhneutson valve or a good set of high precision muffler bearings. 8-)