I have a 99 5.3 ext cab 4x4 w/ 150k and the factory manifolds are leaking quite bad. I'm looking at new studs bolts etc. My concern with the headers are increased heat, durability ( constant leaking) and problems with factory sensors.
This vehicle is new to me and is completely stock ( but not for long) If I could install the headers and forget them for a few years that's what I would do. Look forward to your comments/ ideas.
Thanks in advance.

 

Get a good set of shorty headers. Look at the silverado forum. There is a discussion on this now.

 

I would get the headers.They should come with all the adapters for your sensors,a simple drill and weld in if not already installed.As far as leaking,soft alumnium gaskets virtually eliminate leaks and a couple rolls of header wrap will keep the heat to a minimum.