Well, I'm new here, but I've been going to the drags for years. First of all, they make some tape you can put on your rear bumper so that you don't have to worry about getting rubber on the paint. Forget what it's called though, looks like painters tape, it's blue, and won't hurt your paint. Heck you might even be able to use painters tape...I just never have. I usually wash the car as soon as I get home, and remove any rubber with a claybar.
As for dropping your times...weight is your enemy. The easiest way to go faster, is to go lighter. Obviously, you aren't going to want to start stripping the interior or anything just to post a better time, but if you are running with the wheels in your sig pic I'd bet those are costing you. If I were you, my next mod would be a set of drag wheels. Get some light wheels, smallest diameter you can fit on the car. Put some DR's on the rear, and skinnies on the front. Reducing the rotating mass up front will help shave your times...I've seen people drop as much as half a second with a set of welds.
Icing your intake, and short belting the car can help lower times too. It all depends on how badly you want to drop the time. Usually people do that kind of stuff when they are on the cusp of dropping down into the next full second range (ie, from a 14.00 to a 13.99) etc. Other things to keep in mind...dont run with a full tank, a little less than 1/2 a tank should be fine. I often go with 1/4 tank or less, but the fuel in the tank does help keep the pumps cool so keep that in mind.
I'm tempted to run the 330 a the club track rental this may, but as it's my DD I'm a little concerned about breaking something. I think I'll probably just end up running the cobra or the focus, even though the cobra trans is now in need of a rebuild.