Umm, I would'nt weld the joints if I were you.

What if you ever need to take them off? If the motor needs to come out or a head serviced your kinda screwed. The joints will seal just fine with some exhausts sealer (in a tube) and the aforementioned band clamps.

I personally bought the SSAC headers and the only other thing I had to buy was the sealer and an O2 extension harness.