can you afford a different car or is this your first car for Drag? the cobalt isnt a great one.. but still.
if youre looking at the 2nd race day, i did change my drag car, i just couldnt keep up. my current car now does 1/4 in 7secs and 1/2 mile in 10secs
but if you insist on keeping the cobalt, i would suggest you keep gear ratios low as in the snap up fast rather than taking a long time (is that low or high??) and the final one up so it doesnt rev up and blow the engine..
have the most expensive nitro as you should get four.. then make sure that the nitro will pump it out fast and high, so if youre lucky you will get two goes at nitro on a 1/2mile drag race.
others may have another way of doing so.. but thats what i would do.. hope that helps.