S4drifter,
you mentioned your car might have a 1bar or 1.2 bar spring in it. I'd be worried with a 1.2 bar spring.

Your safe at 1 bar with adequate cooling(good intercooler,additional oil cooler), good octane fuel and enough fuel(enrichment or modify your fuel head).

I've been running with this setup on 7.5 compression for sometime already, pulled my motor apart once and everything looked like it was a brand new engine just put together. I also do track my car once in a while which means pushing it to the limits.

So isit safe to run 1 bar?? Well it has been for me with the right built. I dont know why so many think otherwise.

The 964 3.3 turbo S and the 964 3.6 turbo S both came with a 0.9 bar spring from factory, the turbo 3.6 S did not just come with a 0.9 bar spring but also ran at 7.5 compression. Now please take note that these are factory built cars.

So I belief if your engine is built correct with the right stuff in it, than your alrite running at 1 bar.

 

I suppose 125 is not a high compression - I would expect something like 105-110 based on a 7:1 compression ratio., but I think I have seen some people report numbers above that.

I am just repeating what others have said, but the first thing to do is ensure the injectors are delivering fuel at the intended rate. Flow testing is a worthwhile maintenance item anyway.

Next, change the wastegate spring to 0.8 bar (this will pay dividends in longevity)

Last, I would make the dyno run with a sniffer at the tailpipe and an accurate boost guage connected to monitor pressure under hard acceleration. the dyno run is a controlled environment that allows a much better understanding of the circumstances behind the detontation you are seeing. I suspect something in these three steps will uncover the problem and provide direction for the remedy.

Good Luck - Be sure to let us know the problem when you discover it.

 

FYI, my engine was recently rebuilt with 7.5:1 CR P/Cs, my compression figures are 121 to 125 p.s.i.

Your vacuum can on the distributor is said to be fine? Perhaps the vacuum hoses are reversed, or the boost retard hose is pinched or otherwise occluded?