Looking for opinions /experience with aftermarket exhaust manifolds

[Unilevers]

heat drives turbo's, the less heat lost through the metal the more efficient it becomes.

i use the full tilt ones (the PP on is a full tilt one just resold). It is only useful on a large HP truck and the gains are not really seen until very high HP levels. If your wanting it to help a normal everyday stock truck your wasting your money.