I ran my car for almost a year with LT's and no tune. I knew the car was about to get ripped up, and supercharged so I figured why waste the effort. Car ran fine with no issues. Even made decent numbers all told. Are you making the most power, or is your car running the best with LT's and no tune..no in each case. Is the world gonna end if you do not get a tune immediatly after headers..no.
And..the answer to the original question is in the post below. All the dyno runs we did in the header test below are untuned. It is slightly lean down low, and rich up top.
http://www.camaro5.com/forums/showpo...&postcount=131