Well just from my short time researching boosted LS applications, there will be alot of determining factors. Like for example:
how much power are you looking to make?
What are your goals for the car?
Are you on a stock engine or plan a forged build?
If your planning on a forged short block, how many cubes?
Also things like, do you currently have full exhaust & wish to keep it? If so a turbo is not for you since it runs off your exhaust gases & you'd have to completely alter your exhaust. You also need to think fuel system parts. Depending on how much power & your goals for the car you can easily sink $1200 in your fuel system alone before you have time to blink, LOL.
I'd say $15k for a properly built reliable boosted set-up is about right honestly. If you figure in a new motor set-up(347 would be cheapest), FI kit either turbo or SC, fuel system parts, tuning. FI isn't a cheap game to play, but you can save some money here & there picking your parts wisely the first time around.
__________________  1999 Trans Am Ws6 6-speed--12.9 @ 108.7 w/2.1 60' (street tires)(before H/C/I no new times yet) MODS: MTI Lid--Hooker Muffler--Pacesetter 1 3/4" race LT's--TSP 3" ORY--LS7 clutch kit--LS2 flywheel--224/.581 114--5.3 Bo White heads port/polished & milled .018"--Bo White port/polished TB--Patriot Gold dual spring kit--7.4 TR chromemoly pushrods |