Let me add some info as I have experience with the manifolds.
I have a RWD SSAC manifold on my FWD sentra, Coalition SE-L did it. He had to cut the flange off and have it welded back on angled toward the block. Otherwise, there was little to no clearance to run lines and it would hit the radiator. So, he also had to make a custom downpipe. Now, I am stuck with a DP that leaks like crazy and removing the manifold is near impossible. The people designing it didn't think of the possibility of having to take it back off! There is no room for wrenches and if I can, I will QUICKLY put a stock manifold back on!
The GTiR ones on ebay, they are great. My suggestion, take it to a shop and have the head flange surfaced so it is flat. Once you do that, you will be set. Never seen one crack either.
Brent