I just installed a set of pacesetter headers and ordered an email tune from PCMforless, just got it and will be flashing the computer tomorrow once the cable comes in. My question is, does the computer need time in order to learn everything again after the new tune is loaded. I want to try and get it dyno'd this weekend but won't if waiting for the computer to relearn will get more from it.

Also, I have a slight exhaust leak at the passenger collector, I already tried fixing it twice with no luck. It's not loud, but i can feel it when i put my hand near it. It's after the o2 sensor and not nearly loud enough for the knock sensor to pick up. Will that throw performance off?

 

Yes, it will have to relearn, but it won't take long. Any exhaust leak near enough to an O2 sensor will have an effect on it.