i have seen anywhere between 235 to 270 on various types of dynos... all dynos are configured differently... its pretty much useless unless you are doing a before and after run to test the effectiveness of a mod. otherwise you just have a number that dosnt really mean much. A car that dynos 270whp on one dyno might very well be slower than a car that dynos 240whp on a very conservative dyno. theres also different standards such as STD and SAE...

 

I just dyno'd my stock 05 5at on a mustang dyno and got 234 RWHP. Im going to install a 5/16 spacer, pop charger/ztube, and grounding wires this next month. I wonder what gains I will see