Timing is exponential. Turbo is independant from boost HOWEVER some boost must be set. The amount of timing applied, when the turbo is engaged is NOT dependant on timing boost settings.
The v203 software REALLY should get it done in nearly all applications without turbo. If you're setting your turbo delay below .4 or .5 you're overtiming your setup and I gurantee that you're still off and leaving HP on the "table" so to speak.
Turbo is designed to support not having enough timing boost. If you're using some turbo try adding a touch of motor timing instead. Turbo was not intended to directly cover or cross time the timing boost. I do realize that it does work. V203 is very forgiving to bad setups and setups that aren't ideal.
However if you listen to Lang(isgroup) or others that have seen the light, you will see that once you get the ideal setup you will not have .5 seconds of fall off, you will have a strong run upfront and in the back. It takes time and testing. There are a lot of factors to take into account.