A friend of mine told me that if I installed a turbo I'd have to get it tuned though. Is this true?
I think you can guess my response. You'll need to get chipped for sure. But you will be non intercooler running like 5 psi, so you can prolly go unchipped with SAFC (I hate myself to say it), but since you'll not be in boost, it's not that much of an issue.
I think this is something that is just going to have to be tested. Personally, I don't think the turbocharger is going to help at all with mileage. Not only will it require nearly unattainable discipline to NOT blip the throttle and become drunk with the awesome feel of your car tugging [can you tell I used to own a turbocharged car? =P], but I'm a true beleiever in more air = more fuel = less mileage.
To get the best mileage, I do think we need to look at efficiency, but we need to look at it with using the least fuel. You can create an efficient setup that drinks gasoline.
I think if you're dead set on using a turbo setup, look at getting a small one [possibly much too small for your engine] and using it beyond it's efficiency zone. You do not want to create compressor surge, but if you choose a compressor that plots your engine far from the surge line and way out of the efficiency islands of the compressor map, then you'll be blowing 'hot air' into your engine. This is the only line of reasoning I see as beneficial to having a turbocharger on a car attempting to attain good mileage. I am no guru on turbos, but I have owned one, and do know a little.
As someone else said, plumbing and the rest of the stuff is very difficult as well - the whole ordeal is really a headache.
One thing to caution - if doing as stated and blowing hot air into your engine, you begin teetering on the razor of awesome efficiency and catastrophic destruction. There is a very, very fine line there.
In Europe, the idea is to put the smallest displacment engine (weight reduction) and add a light turbo to get the power up when you need it and efficiency when you don't.
The trick is to get a 1.0L or smaller engine and place a light turbo on it (it may have to be a JDM or Euro-spec model). The small displacment will yield better economy by default, then, when you need it, the turbo's around to get you up to speed on the highway or during routine acceleration (depending on the programming). The trick is to get the ECU to maximize economy (using an AFC, turbo management system, etc.)
The only drawback is turbo lag, especially on the non-diesel models. You step on the gas and a second or so, you get power. It's good for the highway, but in town it may take a while to get used to. But, the weight reduction alone is worth it. If I could do it, I'd take a small turbo-diesel or smaller engine and put it in the Integra...