Traction is such an issue. You can have all the power in the world but if you can't get it to the track then it's useless. Then again even if you don't have that much power, being able to use all that you have can really make a difference.
When my car was in full weight GT form (maby minus the spare and jack and a few other things like the foglights) with nothing but 3.73 gears, CAI, flowmaster catback, MAF, timing, 180*t-stat, electric fan, A/C and smog pump delete it ran 8.8 at 79mph in the 1/8th hooking a 1.9 60ft on Futura Sports 225/60R15.
I did a ton of mods and the best I ever got was 8.4 at 85mph, 1.8 60ft. It seemed the more I modded the easier I had to be on it to keep it in control. My biggest mistake was 17" cobra wheels. I should have gotten something really sticky to put on the turbines so I could run it at the track. I would always justify it with "well it's a street car and it runs 8.4's trim all the time". Well, OK, whatever I was thinking that doesn't mean crap at the track.
I've learned a lot and if I were to do it all over again, it would be done much differently.