I'm replacing a lot of the valvetrain while I have my engine apart. Some people are telling me on their engines when they upgrade the cam and get stiffer valve springs it puts too much of a load on the timing chain and they have to upgrade it to compensate.

Is that an issue on the 4.3's?

Specifically this cam: http://www.lunatipower.com/Product.aspx?id=2366&gid=297

And these springs: http://www.lunatipower.com/Product.aspx?id=2584&gid=322