So at 1.1 bar the ECU would see 1.0 bar approx. This will advance the ignition a touch, should be OK if you run plenty of octane, but you'd really want a knocklink to safely play with an FCD in these circumstances.

I presume the only reason for using such a low defend point is because you are using ECU boost control so you want to shift the aim point?

 

Yes John, using ECU boost control and not a Dawes type device.

I've seen the ECU peak at about 3.8V, so thought it best to set it just under on the FCD.

 

If the engine will take that sort of timing on SUL (mine did) then it should be OK, but not all of them would. I've been emailing back and forth a Deltadash/knocklink/Dawes/FCD user who is using Optimax and booster. Without the booster on a MY99 ECU things were getting retarded quite substantially at about 16.5 PSI, and at fuel cut sort of levels the knocklink was active.

 

My battery went flat and re-set the ECU/Boost gauge, I took it out for a spin this afternoon (driving hard) and the boost peaked at 1.21bar. Question is would a full de-cat H&S cause the car to boost to these unusually high levels?
I'm worried now..