I have a slight exhaust leak at the header collector. How bad would this hurt me in terms of power and 1/4 mile times?

 

might throw off the o2's since the leak is before the sensors... no codes yet?

 

the only code it shows is P0463. I looked it up and it's "Fuel Level Sensor Circuit High Input" My fuel gauge is on crack so that leads me to think that P0463 has something to do with that and not my exhaust leak. I am no expert and could be wrong.

 

For a slight leak, I doubt if you could measure any difference at all. Of course, it should be fixed soon if not for the smell and annoying noise, than the fact that small cracks become big cracks.