What is the gains of a LS3 top end
 

To I have been hearing about installing Ls3 top end on a 5.3 5.7 6.0. What are the gains for doing this? How much is involved in doing this...?

Thanks in advance.
Ski

You need to do a ton of research and see what makes you happy with the numbers.

For starters, those big ass intake valves only work on a 4" bore or better. That means a 6.0 or larger. And they are capable of 500 rwhp with the right cam and supporting mods on a LS3, so that may let you know what they are able to do on a 5th gen and C6 without anything internal but a cam and valve train.