welcome, to tune, there are only a few people that can do that if you buy a limited at 215 hp they can only tune up about 15 to 20 hp
and you can only put a better exhaust and an air intake for another 10or so HP.
Now buy a srt-6 you start with 350 hp ,, Add a SC pulley and a crank pulley, a tune from Josh at MMS, duel intake from NEEDWINGS.com,
exhaust and maybe rear end change you get right at 400 hp = 348 at the rear wheels. With this the car will run between 12.3 and 11.99
@ 115 to 118 mph in the 1/4 mile, without opening the engine to upgrade heads and cams at a high cost you don't gain that much
now next would be to swap the engine with a supercharged V8, now you have(with the same mods you would do on the V6)
U will have 550 to 600 hp. jim