so i replaced the opti, new plugs and wires cause last time on the dyno it had a miss and was running real rich. so i decide to go back tonite, and it dynos LESS. 272rwhp and 304rwtq. last time it made 275 and 312. why isnt my car dynoin the 290+ other bolt on lt1's are??????

 

Not all dynos are the same. Post the graph

 

i dont have way to post it, but the guy said its running fine and that the a/f looked alot better this time

 

So many things can effect the way an engine performs or even the way a dyno performs. Ambient temperature, humidity (not much in MA lately). BTW, how much oil did you put on your filter? Usually when the engine runs rich, the O2's suffer from problems. Also, I don't see where you removed the cats. Running rich with cats is a big problem.

 

well the o2's were replaced with all the other stuff and the cats have been removed. i think alot of the problem was the car was sittin out side of the shop for 3 hours while they dyno tuned a sts gto. it was only around 30 out today so im sure the extreme cold wasnt helping.