If you are replacing the lower intake gaskets for whatever reason, its most likely going to be a metal and rubber gasket, like this.



which is great, if you only want it to seal. If you want it to make the power it use to, then you need to remove some of that rubber, like this.



Then you throw it on a flowbench (or take my word for it since I did this step for WOT-Tech)



And see what the flow difference is.



That is a lot to lose from an intake gasket, so make sure you modify them and keep the engine running its best.