I run 120 pounds at 2000 RPM, but after I changed to Turtle Wax, it dropped to only 110 pounds. I also use Armor All for protection, so I think that has something to do with it. I am running a 2000 GTS here and it seems safe as I use my seatbelt.
I agree on zero, there is a risk with boost, but the word "safe" epitomizes ambiguity here. I would consider "safe" in this context to mean problem free within reason and on a good tune you could hit 6-7 PSI safely, but I think even at 7, you are pushing the envelope, but again this is subjective at best to talk in relation to the use. Anything other than a perfect tune isn't safe, so I would be using WB's, log, tune, et cetera on any TT or SC application and I do all 3 myself. Any time you are pusing things beyond the designed tolerances, in this case NA to SC you are pushing the "safe" zone so the point in which I see is 6.5 or below for my level of acceptable tolerance.
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Now that the prices of virtually everything are going up and up and now that thousands of people are losing their jobs everyday as the US goverment still hands out 10,000+ checks to those people just getting off the boat, I think I will take a boat ride and get in line, I sure could use the money to pay for the gas in my Viper and GTO!
My stock 98 GTS had a Roe sc with 8# oulley and water/meth. It worked great! It probably wouldn't have been "safe" without the w/m. With the w/m it may have been "safe with the 10# pulley?
I don't think any other Forced Induction system can come close to 10# boost until over 3,000rpm.