did you say which manifold is cracked?

but i agree if its the exhaust, then check the cat, if its clogged and your under 8yr/80k it should be free. if it also the cause of the manifold cracking (pressure) then it could be covered as well. However i would suspect the gaskets to blow first.. How have you repaired it?

http://www.epa.gov/oms/consumer/warr95fs.txt


If its the intake, its plastic, you would have a different problem there, i would suspect overheating, or over torque of some of the bolts depending on how that crack is.