turboeing 03 gt

Actually it will cost more like $10,000 to do it right. Turbo is a horrible awful idea unless you are rich and highly skilled/knowledgable about these cars. Essentially you will have to modify most of the car's systems including engine internals, suspension design, engine management, and possibly even the interior if you do a cage.

I do not recommend this at all.
 
Different perspective:

If done right and if the boost is kept sane -- 8psi or so -- there's no reason a turbo 4.6 wouldn't be a reliable, fun daily driver. If I had the money I'dve gone with a single-turbo rather than my KB.

However, the devil is in the details with turbos. Packaging can be difficult: K-member changes are usually needed to snake the new exhaust manifolds forward to merge at the turbine. You usually lose the emissions control stuff like cats rendering the car un-registerable in many jurisdictions. Under-hood heat management is an issue too with the exhaust re-routed and the hot turbine housing right there. Plumbing the compressor outlet to a front-mount intercooler needs to be done too. Fueling issues would be about the same as a centri or PD blower: SVT pump, Cobra pump, BAP on a stock GT pump... Fuel injectors, upgraded MAF (really should do this) and a re-cal.

If you do this go with a complete, bolt-on kit from an established, known outfit like, say, Hellion:

99-04 Mustang GT Single Turbo System - 350 to 850 HP

This is not something you're going to be able to cobble together from eBay and junkyard parts...
 
Don't take this the wrong way, but going by your question I would say yes it is too much for the average shade tree mechanic. Just because turbo installs require a lot and it sounds like you are at the beginning of your search into the world of turbo's. I've helped with a turbo install and I did my own KB install. The KB was much easier, thanks to step by step instructions with pictures and not too much fabrication needed. Don't get discouraged and just say F it and quit. Keep looking and learning about turbos, then make your decision as to if your up for it or not. There are some specific turbo stang sites and subforums so try some of those also and read other peoples instal threads and such. That will probably give you the best idea as to what's all involved and if your up for it. Just make sure to keep us updated. I love build threads.