How many have checked new stock springs? Well I have, they are border line wrong for a stock motor much less more fuel and more boost..
Some of the valve prints on pistons are strike's during valve float. With a low pressure spring and added boost psi, miles & years of heat cycles the weak stock springs just don't cut it.
So for under 100$ new custom specific springs is always a good bang for the buck.. Everything in the valve train is weighed, cam specs, boost & back pressure, rpm, etc are taken into account and out comes a spring that will best suit a build.
After all we know GM didn't spare anything during production on these motors don't we...
Nice. If you have the time, some pics and description on spring shim/setup if needed withthese springs would be awesome too.
With 70,000 miles on my current springs replacement was on my mind. That just made it up. Good more motivation for me, about an hour before I get back and into the shop. Working very slowly on mine, but some progress is better than none.