I'm personally biased to the Vortech because:
1) It's centrifugal, meaning a more linear increase in power than a roots might have
2) The Vortech is intercooled
3) centrifugals generally don't produce as much heat as roots blowers, and therefore, less heat soak directly to the engine (since the Stillen blower is basically right on top of the intake mani)
When I called Stillen yesterday, I asked them about problems with heat like overheating and such and they said that they use the same supercharger that Mercedes, Jaguar, and others use and there wasn't a heat problem. I am leaning towards Stillen, mainly because of ther warentee and there reputation with Nissan, but not sure yet.
Thats 2 much HP for a daily driver, if you plan on keeping the car for awhile. Sooner or later if I had that much HP I would be replacing internals and I just want to bolt it on and forget about it. I don't want to worry about tunning it, ot keeping it tuned. I would love to have 500-600 whp, but in reliaity where can you use that kind of HP safely besides at the track? And you can forget about it if it's your daily driver. I wonder if Stillens intercooler would help with the heat problems?
I have heard that the APS single turbo for the 350 is supposed to be pretty good. I don't think they have releast it yet, but not sure. I am not that nolligable with FI, just from things that I have heard and read. I do need to do a lot of homework before buying something. Also the turbonetics single turbo kit is supposed to be pretty good. What have you guys heard?
If I had to choose between the superchargers, it would definitely be the Vortech for me simply because of the aftercooler.
Also, if I had the choice, I'd lean more toward the GReddy twin turbo kit than I would the supercharger. They're quick spooling turbos with hardly any turbo lag at all. When I get a 350, this is the option I'm going with.