My experience with standard Racing Beat headers (thick wall mild steel - .125") is that they are good for about 12-15 weekends before they erode and you get a hole at the outside radius of the front pipe , i.e., the one with the bend closest to the exhaust port. I've heard rumors that this is partly a function of RB using low grade steel, but I don't know a simple way of determining that. However, the failure mode is weird looking - the tubing progressively loses thin layers of steel until it gets very thin, and then burns through. So if your 16 gauge tube is not a much higher grade, I wouldn't expect a long life. Maybe aluminized exhaust tubing would be better, but I have no experience with it as the primary header tubing.

Thin wall stainless headers are far superior. The ones I've seen (RB and ISC) have never had a holing problem. They occasionally crack at the flange and require rewelding, but otherwise they are quite reliable. And they weight a bunch less than the thick wall, mild steel pieces.