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As the others have stated you haven't really done much to change the engine performance except for the tune and cold air intake. Sounds like a reasonable result. How does it feel to you on the street? If you are happy with the real performance don't worry about chasing a number. A nicely tuned up c5 will still get you in plenty of trouble.
Mustang Dynos tend to read low, so the numbers are within reason. As others have said, a dyno is just a tool.
It is just like a scale. Every scale will read your weight a little differently. When you are trying to lose weight, the key is to measure against the same scale all of the time. The same applies to adding horsepower. When you do more work on the car, then the next dyno runs should be done on the same machine to see the effect.
The outcome of Dyno with all that was done gave me 285 at wheels and 365 at crank
You keep saying, "with all these mods", but your choice of mods aren't adding any HP, other than the Blackwing. You need to post your dyno sheet to get more accurate advice.
You have to scan your sheet, and create a photo in .jpg format. Then sent it to your host, or use the CF photo section to host for free. Corvette Forum is slow, but it's here.