Getting informed is the bet way to go, if folks haven't given you that hint so far.

I sort of ramble on for a while and I apologize. There is a bunch of information that can be covered and there isn't even enough room here, so I kinda ramble on for a while.

This is a very religious topic and I try to stay as neutral as possible. There definitely is a lot more to a turbo setup, no doubt, but have more flexibility on how you can use it.

BlownGoat mentioned my favorite supercharger book: Street Supercharging.

If you haven't picked it up, go buy Corky Bell's book: Maximum Boost. It will explain to you everything you ever wanted to know about turbocharging. And I do mean everything.

I've designed several kits myself on either side, and been involved in a Vortec "Blowzilla" install on a Ford Lightning. Nothing like a 675hp truck. I also lined up a twin turbo setup for a friends Roush Mustang that was setup for the street at about 400hp. It also isn't uncommon to see some race cars with insane amounts of power coming out of their engines, case in point any of the drag cars you've seen and any of the F1 cars you may not have seen. Many of the F1 cars commonly put out well over 800hp from a sub-1 liter engine. The early F1 cars were on the verge of topping 1500hp. Of course the blew up every race

You can mix and match as you've probably seen elsewhere. Turbo + supercharger to supposedly get rid of turbo lag, supercharger + nitrous, turbo + nitrous, etc. Interestingly enough, turbos have an easier time with nitrous. A properly designed turbo install will have no noticable turbo lag. If you want to get into the hi-tech turbo world you can use a variable geometry turbo like the ones offered by Garret and the Aerocharger:
http://www.aerocharger.com/

Variable geometry turbos can "look" like a small turbo at low exhaust flows and a big fatty at higher exhaust flows, and to top it off many of them are boost pressure sensitive so that as your max boost pressure is approached it will modify it's geometry so that you can't overboost and hence don't need a wastegate.

If you want to play with an on-line turbo calculator check this out:
http://www.turbocalculator.com/resources.html
Found it on accident the other day.

As far as my experience goes, you can do pretty much whatever you want with forced induction. All forced induction systems will inject a certain amount of air temperature increases with the boost pressure increase, which is why an intercooler of some sort is important. Even a moderate boost level of 6-8psi can potentially increase the air intake temperature after the compressor a couple of hundred degrees, depending on where you are. A properly designed kit would use an intercooler/aftercooler and not water injection to control detonation. Here I will give my opinion: water injection is an excuse for a poorly design system. I don't care what their purported advantages are like "steam cleaning the inside of your engine" or whatever. If detonation is a problem, fix the root cause of the problem. Don't add something else to get around it. Please don't flame me for this, opinions are free and you get what you pay for

You can use a roots, centrifugal, or whipple supercharger. Keep in mind that they will all be belt driven, and will all require power to make more power. So there is a reasonable limit as to how much power you can make because of the crankshaft harmonics that the additional strain the pulley will make. I have seen an interesting supercharger failure where the crankshaft key sheared off under high boost conditions. Fortunately this happened on the dyno while it was being tuned and not on the road! If you do get a supercharger kit do yourself a favor and spend the extra money to buy an aftercooler.

Turbochargers are not without their own flaws as well. Their plumbing can be much more complicated, and a complete system should include at the very minimum:
the turbocharger(s),
an intercooler, whether air-to-air or air-to-water
the appropriate exhaust manifold(s)
the blowoff valve(s)
the bypass valve(s)
all of the necessary plumbing (oil lines, intake, exhaust, etc)
You'd be surprised what many shops tout to be a "complete kit". I've seen too many people buy a bargain kit for $1000 only to find that they need another $1500-$2000 in parts to complete it.

A good example of good turbo kits and turnkey engines would be the ones provided by Banks Engineering: http://www.bankspower.com/twin-turbo-products.cfm
Their current kits are capable of a good reliable 800hp. Their crate motors are available with up to 1200 hp. Gale has been in the business of turbos for a very long time, building everything from land speed record holders (like a Dodge Dakota pickup 222.139mph top speed and still gets 21.2mpg on the street; must be nice to have 735hp and 1300ftlbs) to off shore boats with multiple 2000+ hp big blocks. Other manufacturers make comparable kits for other makes too, Cartech, etc.

Best thing to do is call the shop you're interested in or visit them (if you can) and talk to them first.

--nevets