The STG-I Dinan/Vortech that I had on my 99 was estimated to produce 350 BHP (crankshaft) with NickG's software. I'm 99% certain it was running 7-1/2 to 8 psi. It's been a while since I've given it any thought, but I was thinking the next step up was 11 psi (by using a smaller pulley diameter) and that after-cooling was recommended, if not a requirement.
With STG-I and 7-1/2 to 8 psi setup, and given average use (with proper AFR software management) I doubt it would have much, if any effect on the engine's longevity. The biggest problem is that a little boost is like a shot of heroin; it makes you crave more. I call it boostitis, and then you're soon looking at ways to run a top-mount turbo and trying to reign in 600 rwhp
1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yello Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon