Dont forget though that tuning a load or speed area has an effect on the sites either side of tune.

Example.
YB's tend to det badly at 5500rpm.
Using an ecu with sites at 4000 5000 6000 & 7000 you would have to tune the spark out of the 5000 and 6000 sites to get a good solid figure at 5500.

Unfortunately, this wil have had a similar negative effect on speeds between 4-4999 and 6-6999 due to this same interpolation.

Having a load site at the correct place would fix this small but very relevant issue.