So the JB4 works for the Stinger as well, so you can use that to get a good amount of extra power, BMS sells a kit that has everything you need to make 400AWHP or 420-440RWHP depending on what drivetrain you get (AWD is faster in a straight line, RWD is better for track, Though keep in mind, ALL the AWD stingers can become RWD with the Pull of a fuse, you just still will have the extra 300lbs of the AWD system)
The BMS kit is about 1200USD on average.
you can also add WMI to make more power with the JB4, in some cases on here, above 500AWHP with other supporting
mods
HOWEVER, if you really want to go fast, you need to get a dedicated ECU tune from either Lozic motorsports out of South Korea,
or
a Lap3 ECU tune, which are out of one of the Carolina's I believe.
While on paper, a dedicated ECU tune wont put that much more power down compared to a JB4, they WILL be significantly faster, as both ECU tunes can manipulate much more data for the car in real time.
There is actually a thread on this forum that has a list of the fastest 1/4 times that stingers have achieved, the fastest on record being a 10.9 right now. each of the top times lists at least all the big
mods that each car had.
to answer your questions in order specifically
Dont go big turbo unless you TRUELY dont care about warranty (Also the only kit out there is like 12K)
Stingers love Meth more than your average Addict
A RAD is only needed if you plan to do Multiple high speed passes in a very short timespan, however it will give a couple extra HP because of the extra cooling even in general use, and some of them just plain look really cool on the car
the ECU's are not locked, but they are on the more complicated side of things which is why only a few shops are really good at tuning them
to get into the 10's consistently, you will need the following
ECU tune
TCU tune
WMI or e30/race gas
Intakes
at least a full Catback exhaust if not a primary downpipe as well
an Front mounted intercooler is probably a good idea
a Damn good Tire
Driver Mod
It will probably cost between 5-6K when all is set and done.
Mind you, this will be a high 10 second car on the drag strip, not the street. the street will probably run low-ish 11's
Link to the top times
Drag/Acceleration - The Official 1/4 mile track thread.