Does adding LT Headers require a tune?

I did a search and couldn't find anything other than people talking about their own headers.

Is a tune required with LT headers and exhaust?

What was the mileage gain/loss you experienced?

Yes, especially if you run no cats.

Mine stayed about the same but I'm at 4800 ft. Down at sea level I gained about 1 mpg and was noticeably louder.

Yes you will need a tune because of the oxygen sensor moving. The last thing you want your truck to do is run lean because the 02 sensor is further down the exhaust.

No you don't really have to. I rocked mine out without a tune for weeks before I got a tune. The tune just makes the truck fun because it feels completely different after the tune. But now I did disconnect my battery for the entire weekend while installing my headers. You have to do a complete reset of the computer and do a drive cycle with it. I never once got a CEL and I was romping on it pretty good before the tune.

CEL will more than likely come on. It's also not going to sound right. My truck with the stock tune on it sounds like shit compared to when it's running the performance tune due to the shift patterns.

Yes. I had the CEL on and cold start wouldn't work until I reloaded a tune for the headers. Extremely loud on cold start and at WOT

Takes a **** on the warranty though. haha

Personally, I wouldn't bother with headers if you're not going to retune. You can't extract the gains from a mod if the truck thinks it's stock.