Funny.

I dyno'd 239 bone stock at AAM in very cold, clear weather.

I added spacer and exhaust and got 250 on a different day.

I got a re-flash and only got a couple hp on top, but picked up a lot in the mid range. From 4300-6000 I gained a consistent 10+ hp. From 4000-6000 I picked up about 10+ ft/lb torque. These gains make a big difference in the pull you feel once you get up in the revs.

I didn't have an intake when I got the flash done, so I don't know if this might have hampered my ability to get top end power.

 

Is it true that dyno's can have up to a 5% margin of error? That would be like 15hp on our cars right? My buddy told me that he's seen supra's get over 30hp difference from back to back pulls and no other changes.

 

Yes, quite common actually

 

So in the worst case scenario, you can get over 10hp off on each run. So if you do 2 runs to see before and after mods, you can be close to 25hp off?