I've been asking a LOT of questions regarding tuning the PCIIIr for the Busa. I haven't messed with the timing yet. So far what I've been able to gather is to get the fuel curve down first.
I've done a little experimenting but am pretty uncomfortable messing around with the turbo without some kind of A/F indication. I'm considering adding an O2 sensor and A/F gauge to give me some feedback while I'm driving.
The difficulty with advancing the timing is the absence of a knock sensor. I wouldn't think that retarding the timing a bit to smooth the response would be a problem. How will you determine when you have 3 degrees advance? I don't think the PCIIIr table entires are in degrees. I think they are arbitrary values.
I'm by far no expert engine tuner. I am doing a fair amount of reading and trying to learn. My main goals are smooth power delivery and not melting down the motor under boost.
At the moment I'm considering a heated O2 sensor with the AutoMeter A/F gauge. I'm giving some thought to a wideband sensor. However, those require a special meter or a voltage adapter. O2 sensors are 0-1 volts while wideband are 0-5 volts. These devices are not linear so I'm not sure about the conversion. The question is whether the meters are linear or attempt to correct for the nonlinearity in the sensor. Since most discussions indicate the meters are more accurate in the stochimetric (sp?) range, where the sensors are most accurate, I would assume that the meters are linear. Therefore the voltage conversion should be easy.