Broken PRC ls6 heads... What to replace with? MS3 Cam

So I'm trying to decide which heads to replace these with. I'm HOPING TSP will throw me a bone as they told me these were from a bad batch in 05, they arent going to send me free heads or anything but you know some gaskets and free shipping would be great!
Basically I need to know the real differences between the stg 2.5 5.3 heads they offer, and the stg 1 ls6 heads(Much revised since my version) they offer now.
I've done my searching and what not, I want to know if people are making more low end torque out of the 5.3 heads, or more power across the whole board including peak?
Or is there another budget head out there that I should be considering? Keep in mind this is a bang for the buck job, I already bought heads once, I wasn't planning on buying the same heads again to replace them. Nor to I want to spend 2k on a set of non-GM castings.
Anyone had any luck with the trick flow as cast heads? Flow numbers? Dyno sheets? If I'm lucky a dyno sheet with an MS3 cam?
Thanks in advance.
-Mark
They have better valves, often more compression and ive seen better dyno numbers out of the 5.3 heads than the stg 1 ls6's...the stg 2.5' ls6's do slightly out-edge the 5.3's.
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After 3 years, it is hard to positively link this head to the run that had some core shift issue. The ports have indeed been updated since then to add more material to the roof of the port. However, we are constantly updating the port design looking for more air with a smaller volume runner. If you search here you will find more cases like this where the factory casting will break.
https://ls1tech.com/forums/generation-iv-internal-engine/980272-what-all-else-could-wrong.html
For the mods you have, I would go with the PRC 2.5 5.3L heads. They will bump the compression up along with a little smaller CC runner than the LS6 head. Also, we can get these heads to clear with the larger valves. We have numerous cars with these heads and cam making 470+ RWHP without having to flycut pistons!
If you are wanting to go with the PRC heads again, shoot me a PM and I will take care of you on another set. We can set them up without springs for you with new seats and seals installed on the heads so you can just carry your springs, retainers, and locks over to the new heads.

Thanks!
Jon Reynolds
After 3 years, it is hard to positively link this head to the run that had some core shift issue. The ports have indeed been updated since then to add more material to the roof of the port. However, we are constantly updating the port design looking for more air with a smaller volume runner. If you search here you will find more cases like this where the factory casting will break.
https://ls1tech.com/forums/showthread.php?t=980272
For the mods you have, I would go with the PRC 2.5 5.3L heads. They will bump the compression up along with a little smaller CC runner than the LS6 head. Also, we can get these heads to clear with the larger valves. We have numerous cars with these heads and cam making 470+ RWHP without having to flycut pistons!
If you are wanting to go with the PRC heads again, shoot me a PM and I will take care of you on another set. We can set them up without springs for you with new seats and seals installed on the heads so you can just carry your springs, retainers, and locks over to the new heads.

Thanks!
Jon Reynolds
We'll see what happens though.
I'm not sure if they are even compairable to the 2.5 5.3 heads flow wise either. But I may be wrong. Anyone got a flow sheet for these?











