If installed properly, you shouldnt have any of those issues with headers. (the collector crack is something else entirely, problem with their build is my guess)
But Mac makes a good affordable set of long tubes and shorties. I had them on my 3.8, long tubes and offroad h-pipe. I would push them on anyone.
On the other hand It was my understanding that our stock manifolds were a header style build anyways, which will minimize gains by aftermarket, it will however improve sound.