Originally Posted by KennyPowers

I seem to be in the same boat here.. had a 996 911 Gemballa 650 was a monster of a porsche.. got rid of it and years later gave the z06 a try... Liked it so much I ended up getting a backup..

From the factory the Z is VERY capable, a few upgrades and you have a full blown race car, and in factory trim it handles like it. I pulled the heads on both and sent them off immediately.. went all factory parts and plan on "servicing" them after a few seasons of track time.. PASAGEMAKER with 6! NICE!!

Originally Posted by gsflyer2011

I watched a very interesting video from a well known Corvette shop owner. He said 2 things. Don't modify your engines and secondly rev up to 6500 rpm only. You are not getting much in top 500 so why stress it. That way you will never have head problems. Also following this subject for many years, the ones with head problems are most of the time if not all who have modified their engines. That is my impression.

Originally Posted by BuckeyeRay

You watched Lyle from C&S spout the Company line in order to keep from offending the GM guys he was talking with. And they said 6k, not 6.5k. It's BS. They know there's a problem else why tell us to cut off 1k short of redline in a car they intended for the track?

Originally Posted by tommyc6z06

pretty much the same...I went with AHP pkg 4 at 10,000km (6200miles) for peace of mind as soon as I bought my car. It was 10yrs old at the time and my local Porsche guru did the swap (didn't know anyone local in the LS world yet). Labour cost CAD$1800 (about USD1300).
These were the "wiggle test" results on my original heads (with valve springs removed)...and, yes, I know wiggle tests are no longer deemed acceptable by the sages. I was told any measurement over .008" is considered 'out-of-spec', and, if I recall, AHP specs .005 on their reworked heads as measured with a dial gauge.
Cyl 1
Int- .008"
Exh- .005"

Cyl 3
Int- .008"
Exh- .005"

Cyl 5
Int- .009"
Exh- .006"

Cyl 7
Int- .007"
Exh- .005"

Cyl 2
Int- .010"
Exh- .007"

Cyl 4
Int- .008"
Exh- .006"

Cyl 6
Int- .010"
Exh- .006"

Cyl 8
Int- .009"
Exh- .007"

So, several guides were borderline and some just a little over.
I do track the car a little, but kept the engine stock for reliability and longevity...its fast enough for me, and I can always try driving it better. Anyway, mostly just a cruiser that is meticulously maintained and treated very gently and lovingly.

So...the question is, would the stock heads have lasted? would there have been issues? I'll never know. But at least I've mitigated risk and feel ,much better about that.
I'll add that unlike many, I've also done what I can to reduce high temps on track, which surely don't help with overall engine wear anyway, and I also avoid lugging the car in 6th (ebb/flow of traffic), or loading the engine at low rpm in taller gears...which is easy to do with such a torquey car, but I feel may also introduce some undesirable harmonics which may also exacerbate some other issues noted with these cars.

Anyway, sure, there may be a lot of internet/forum hype, and I personally know people with high mileage untouched LS7s, as well as others with modded engines that have become 'maintenance items'...even used on street. But, unlike some other areas that I regret having blown $$$, I have no 2nd thoughts about having 'fixed' the heads and would do it all over again, the same way.

To each his/her own