What you need is:
1) large flat metal surface
2) Sticky backed sandpaper
3) elbow grease
The manifolds were warped on our 5.7 Grand Cherokee, being El Cheapo laid 80 grit sandpaper off a roll on a good known flat steel table at work and sanded them suckers flat. (Note) also worked to increase the compression on a old Polaris 250 quad head.
1) large flat metal surface
2) Sticky backed sandpaper
3) elbow grease
The manifolds were warped on our 5.7 Grand Cherokee, being El Cheapo laid 80 grit sandpaper off a roll on a good known flat steel table at work and sanded them suckers flat. (Note) also worked to increase the compression on a old Polaris 250 quad head.