Re: 4.7 turbo!
The 2005-07 4.7's are rated at 235 hp and 290 ft-lbs. The 2008-09 are 305 hp.
An extremely efficient engine will gain 50% in hp with 7 lbs of boost. A stock engine is not "extremely efficient" and as such will only gain around 7-9hp per pound of boost. These numbers are well known, and proven, in the turbo world, so i am quite confident that they're accurate. Yes, there's always some wiggle room but not that much. 7lbs will put a 235 hp engine into the 280-300hp range. Proper sizing of the turbo will ensure a strong torque curve and no lag.
Turbo sizing is very important for a street driven vehicle. Smaller ones will spool faster but have a limit of possible horsepower. Big ones will produce more AIRFLOW and thus boost but if you don't have enough airflow through the engine to spool it properly, you'll have huge lag (the time between pushing the throttle to the floor and the turbo spooling up to produce usuable boost) The nice thing about turbos, is that they are very efficient at producing power and torque. Add that to an engine that is also designed for torque and you have a recipe for fun! 300hp isn't alot these days, but imagine that the same engine now makes 380-390 ft-lbs of torque! Torque gets you moving,so you'd have the off the line grunt of a Hemi, without the weight penalty.
You need one sized for a 4.7 litre engine (cylinder count doesn't matter) with a hp goal of around 300-350 at 7lbs of boost. You use that information to read a compressor map for a given turbo and find out if its suitable.
Going to ebay and buying the biggest turbo for the lowest price will give you terrible performance on the street and a possible blown engine.
Here's an example:
Borla S catback.Stillens. BT catch can. Hemifever tune.