Welcome to the forum. 8 psi is what is considered safe for a 5.7 with stock pistons/rods/crank. Throwing NOS on top of that is a bad idea on a stock rotating assembly. As for which supercharger to buy, it depends on your goals and how you intend to use the car...weekend warrior or all out racer? The choices are turbo, procharger (centrifugal), magnuson (blower), or whipple/KB (compressor). Each have their advantages and disadvantages.
Turbo - a little more complicated to install and a little slower to build boost early on but when it does watch out.
Procharger - builds boost/power linearly so easier to get traction off the line, air-to-air intercooler yields lower IATs. Does not require disassembly of the intake but crank should be pinned. Seems to be a good choice for racing.
Magnuson - builds boost instantly so traction from a dead stop will be difficult. It does not whine like a whipple or KB but still makes great power and reliable. Blower unit replaces the intake and crank needs to be pinned. Lots of guys running maggies as a daily driver.
Whipple/KB - similar to a maggie but they tend to make more boost/power and have a pronounced whine like the HC.
If you want to know what kind of power some of these units can produce on a 5.7 check here.
Not sure if this has every been posted, but I consolidated the customer builds performed and posted by API into a list (sorted by highest HP to lowest). Hopes this helps some folks narrow down their power adder options for the 5.7. I may add approximated HP/Dollars later on. :smile:
www.challengertalk.com
Dyno sheets of built up cars can be found here:
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BTW cost of adding a SC will run between $6000 to $8000 depending on the route you take and make sure you upgrade the fuel pump or that it is up to the task to provide fueling for the extra power. Also be prepared to upgrade the driveline along with the brakes. If you want to make the most of the supercharger you will want to run long tube headers and a cam ground for force induction (the 6.2 cam is a great budget cam).
Good luck.