they should take the area above the stock dyno line and from it subtract the area under it and give a value this way you have a better idea of what kind of gains are to be had with a mod. The gains then become quantified by how much power/torque is useable. example: CAI's usually result in a loss of low end torque/power but result in a gain in the higher end, but imagine if it lost a LOT over the stock dyno and the peak was a lot higher the manufacturer of this cai can claim "peak torque gain of 10hp" when in fact the total area under the curve between the original dyno and the with CAI dyno result in actual gains of zero.

 

You talking about integral, right? Sure you can do that, but it's same as using small nuke to rid your house from mice.
There're always be dips and peaks on dyno curve and visual inspection is sufficient enough.
Taking integral will not tell how much power/ torgue is usable it will just tell whether you have gain or loss over entire range. So some mental effort is required-loss at 1500 will not bother me(even 10 hp), but loss of 5 hp from 2500 to 3500 would, again gain at 7000 wouldn't matter, but at 4500-oh yeah!

Alex

 

like i mentioned, i did say it's importna to see the actual graphs to know where the power gains/losses are.

furthermore, the area does indeed tell you how much power/torque is useable in straight line sense b/c in for straight line accel you ARE using the whole rev range in each successive gear. Plus i did mention that comparing to compare the peak torque range of two products you STILL ultimately need to calculate the area of the rpm segment being compared, so useable hp/torque in a set range is still important comparing product a to b.