NovaKeagan

I'm in the process of building a 5.3 L33 for boost. I'm running the stock cam as I am using a 6 speed standard and don't require a longer power band.
I plan on running around 15 psi of boost, what springs should so upgrade too?

IGN-1A

Hi, I have fitted the LS1511ML PSI valve spring set for your application, NEVER had one fail.
Lance

NovaKeagan

Just for security of my engine, what helped you determine these springs for this application? Do you also mean stock cam aswell?

IGN-1A

SURE, the Exhaust Pressure (EMAP) can OPEN the exhaust valve on the Intake Stroke, not good.
The 130# seat pressure will keep BOTH valves on the seat @ 15 psi/MAP/ 30 psi/EMAP.
This spring has lower nose pressure, good for your stock valve train (longer life)

TurboBuick6

iTrader: (2)

For a stock cam, I would go with standard PAC-1218's. Very low stress spring and will last a long time.

TrendSetter

pac-1218 are a common 'go-to' spring but those psi springs lance mentioned are a really nice, premium choice.

SharonPerry

Yes, they are good.