As for the warranty, it is basically this, when you open your engine, to install heads and cam. There will be no further warranty on the engine, or the way it runs, including oil leaks.
Justremember, your engine will idle at 950, and you loose torque below 2300 rpm.
When you cut the converter assembly to install the long tubes, you void the converter warranty of 8yr80000miles.
Please keep this in mind, c4c5