I have a 1999 ext cab short bed z71 and would like more power. What would it take to fit a 6.0 into it. Or maybe some new calibrations and upgrades to the 5.3 would help? trans: 4l60e, auto trac transfer case 70K miles.

 

A 6.0 is a drop in engine. everything will bot up from the 5.3 and is suppose to be pretty easy. Or you could work on the 5.3 with some long tube headers, stall, tune, and maybe a supercharger. their so many different ways you can go. Also your budget has alot to do with it.

 

Just got my 6.0 for $1500 shipped to my door with 6 mo. parts & labor warranty.
Start calling wreckage yards. Most offer a warranty with them if you ask.
Car-part.com is a good place to start.

 

Thanks alot will I need new pcm or harness?

 

Nope, no new harnesses, etc. It is a complete direct bolt in.
...although you will need to have the pcm re-flashed.(nelsonperformance.com)

Another thing.....like I am doing, you might as well put a healthier cam in it while you have it out as listed in my sig.

 

does GM pcm need exhaust backpressure to function?

 

Not sure about the back pressure but one thing to consider is making sure you get the new 6.0 injectors as I believe they 99s were smaller then 00+. Don't quote me but just trying to help.

 

First, check out your Knock Retard. I bet you're getting the typical 8* almost all 99s and some 00s had...