Originally posted by Rob Scala Too many stories of Driver's side replacement headers cracking not long after replacing the cracked factory one! Trying to avoid this!
Have one tig welded by a competent welder (one who is used to repairing cracks) and you shouldn't have problems. The trick is to remove all the crack, even if it means routing the old 3-5 tube weld out completely and rewelding it (TIG of course).
I've seen a lot of people just try to "cover over" the crack with weld and get about as much penetration as Mini-me. That won't work and if any crack is left, it will propogate into the new weld in short order.