You could be totally right on the cores, I didn't even realize the 5.3ls had vvt till today. I would suggest a stall next but I would go with a 2600-2800 to get some more out of the hole. Otherwise gears are obviously an option. I'm looking for FI on mine and ditch vvt or at least a boost friendly vvt. Still researching as of now. Stall really helps it move and I would suggest it.

 

5.3's sure do come with vvt
I learned that when I had all my parts and popped my front cover off and went "wait....whaaaat" and I actually fired an email off to iamkeniff and was like "seriously?" haha so I was to far into it to do anything other then order a 4.8 cover and delete it!

 

Man that sucks , I only had two days to do my swap lucky me my stealership had a phaser .like a dumass I didnt follow directions and ruined the stock one dam thing is $140
And then the valve cam bolt is another $55

But whatever I love the cam was alittle surprised pat gave me those specs but in the end it worked like magic

 

there is a sticky in the gmt900 section about the cam cores and vvt cams.

 

Not only do you need to find the right core, you also need to make sure the cam grinder grinds it on the right core. I had to stay on (not gonna say any names) *** to make sure they ground the right core because they almost screwed up after I gave them the phaser number 3 times....