AFR was 7.4, is there a way to derive the boost from that? Maybe 8PSI?

 

ahh No on both of those numbers. Stock boost is around 21 for the X I think.

 

what shop tuned you if you dont mind saying. Also you have to consider Cali's finest 91oct is a power killer

 

There are several things to consider here. First, get a boost gauge. It's not safe to be modded and tuned and to have no way of knowing what you are boosting.

There are many factors as to why your numbers may have been lower than what you expected. Was it hotter today than the last time you dyno'd? Were you on the same dyno? There is nearly a 15% difference between mustang and dynojet dynos. There are even sometimes differences between the same kind of dynos that are just at other tuning facilities. Was the boost higher? Lower? This is why you need a boost gauge.

Ultimately there are too many variables to figure out why your numbers don't seem right.

 

Who tuned your car?

 

post a graph, and who tuned the car.?

 

yeah who tuned it and what was the baseline.
dyno #s are for bench racers,
the dyno is a tool to tune and the only thing that matters is the delta
if you baselined at 205whp then it just happens to be a real low reading MD

 

Well I made 305whp on a low reader MD, and I've seen 340whp on a local DJ. So lets say your 280whp may be 320 or so on a DJ which isn't bad.

Also dyno numbers mean nothing. My car runs like a bat outta hell for 305whp, I clicked off a 7.9@88mph in the 1/8th, and have no doubt my car would run low 12s@112+