Jonas,
I run my SP60 on near stock fuel. I have removed the fuel pulsation dampener and increased the fuel pump voltage to 18v. I am paranoid as hell about breaking my car after blowing a turbo. I DO NOT WANT A BLOWN ENGINE. If you get good gauges, boost, egt, A/F, Fuel Pressure, and keep your eyes on them then you shouldn't have a problem. ALSO you need to tune your car conservatively. There is no sense in pushing your fuel system to the limits.
Also you must have your injectors cleaned and balanced. If one is clogged, kiss your engine good bye.
I would definatly stick with a smaller turbo, SP60 or less, or possibly a PHR Street, or Stage 1. Anything more and there is simply too much risk. Also it makes no sense to go any bigger on stock fuel because you will never be able to achieve the full capabilities of the turbo.
Things have worked great for me so far. I've taken it on a lot of hard pulls to over 140mph. My car was running a bit too lean in the upper RPM range so I didn't take it any further than that. I was afraid to tune my car myself, I had presumed that Lance at Toyomoto would be able to tune it for me.
Anyhow, after months of delay, I went ahead and tuned the fuel a little myself. Car runs like a charm now. I hope to get it on the dyno when I get back in town sometime in December.
Hope that helps some.