slant timing with turbo

Its a bit of a misleading infomercial.
The limiter is very clever idea IF that's what is needed.

It depends on where the curve needs to be adjusted.
That will depend on the curve the distributor has in it now.
Proper Timing depends on the speed of the combustion process and the speed of the piston.

You also will need to know what you want it to do when boost kicks in.
The turbo will change the compression and heat input.
Will you want to reference it to know when the turbo is spooling or just assume it is?

Successfully turboed slants are out there. See what they are doing. Even the EFI ones can be informative. The timing will be about the same so you can look at their tables.