First thing is first. Unless if you're going to get an aftermarket plenum, doing internal motor work, or going boosted, ditch the 70mm throttle body. Sell it on E-bay or something. It's not going to help you with your times and if anything, its only going to cost you. You dont have to take my word for it either. White99GT has the dyno results from where he added the 70mm throttle body and it didnt help him one bit.
I take it you have a five speed. In that case, you can hit 12's with the 3.73 gearing. However, it would be easier with 4.10's or 4.30's. If you dont believe me, look at all the top racers on these Mustang Boards that are n/a. They almost all use 4.30's. I look to be joining them.
Aside from the gears, you need traction. Good performing street tires are not going to cut it. You need at least a set of sticky Drag radials. Personally, I recommend investing in a spare set of 15x8in. drag race wheels and throw some ET street or drag slicks on them and use them at the track only. To further increase traction, a set of good performing upper & lower control arms will go a long way.
As for weight, you dont have to dump the rear seat to hit 12's. However, I do recommend dumping the spare tire, jack, and tire iron to shed some weight. If you're worried about a flat, either leave all that stuff in there or just pick up a can of "fix-a-flat" at your local auto parts store. Yes, the stuff actually works and you dont need to jack your car up and put on a spare tire either. I keep a can with me at all times.
As for exhuast, I see you've already got some flows and vrs o/r x-pipe. If I'm not mistaken, Mustang92(Bill Putnam) used to use one of those vrs x-pipes and had good results with it. So your fine there. A set of LT headers would be a good investment, however, that will be really expensive. Its all in what you want to do and how much you're willing to spend.
If you really want to hit 12's, the fastest way of doing so is with boost. However, I'm not going to BS you either. Its also the fastest way to ***k your motor up and in a big way. These cars come stock with hyper-reutectic pistons. Although they are lightweight and rev up good, they are not very durable and have been known to shatter under boosted conditions. Should you invest in boost, I strongly recommend setting aside money to upgrade your pistons and connecting rods to forged steel for increased strength. I'm sure all the guys on this board who've been using boost for an extended period of time will agree with me on this point.
Aside from all of this, the best thing to do is practice, practice, practice. This is the key to lower times as the more you pratcie, the better and faster you become. I strongly recommend you take a look at the fastest n/a racers on this board and take advice from them. Mustang92, Automatic Weapon, KenB, TruBlu01, and Kurgan are a prime example of the guys to ask. Let us know if you have any other questions.
