Here is reply by Bill Marino (a DSM specialist from NY) to a similar question:
"As long as your car is in good shape and nothing major is wrong this is what will put you in the 12's
Free mods can be found on VFAQ.com
Joe P MBC and boost gauge ( boost controler )
Cat back ehxt or look for a full 2.5 inch system with a test pipe
95 Ehxt manf and porting work. Port the 14B and o2 housing.
Now this with TUNING will make 12's but it takes knowlage to do this. Things like Timming advancement and leaded fuel and tuning tuning tuning will get this done. I can personally do this for under $1000 but I do all my own work ( and porting and discount on parts but hey that's just me ! =-)
Not hard and not really a lot of work. 12's would be fast for this combo but I know people that have gone faster with less but I am not going to tell you to blow the car up! =-) you should use a DMM ( Digital Multi Meter ) to keep a eye on the o2 voltage.
That about covers it. For high 13's, a MBC and free mods, and cat back might be enough.
Long Island, NY