you can make either one last even with higher boost...boost doesn't kill pistons/rings, detonation does. If you wanted you could possibly run 12-14psi on a stock bottom end, but you would need good race gas, retarded timing, and probably alky injection to do it, and it would have to be WELL tuned to not blow it up.

There are some guys in GN's running 30+psi pressures on stock style cast pistons...they aren't hypereutectic, but they aren't forged either...they tune the CRAP out of them.

 

my stock motor has survived since this past summer just fine. my qmp kit has been super.

 

I guess this turned into another turbo LT1 vs turbo LS1 but FWIW...

Perhaps the reason an LS1 holds up better at higher boost/HP level is a combination of these things

1 Lower compression
2 Better PCM with dual central mounted knock sensors keeps a better handle on preignition, which is the reaper for either of these engines.
3 Better flowing heads which skews the boost comparision. An LT1 with 7 lbs of backpressure(boost) in the intake isn't getting the same CFM flowing through it as an LS1 with 7 lbs.

All that said if you're going to FI the LS1 with a stock bottom end the best thing you can do is pick up a set of the cheap and readily available 6 litre aluminum truck heads. These combined with a little thicker head gasket will get you close to 9:1 and flow even better than the regular 5.7 heads.

 

FWIW, compression should never be dropped by use of a thicker head gasket.

 

In theory no, but lots of people do it and it works.

I ran 15 PSI and over 600 RWHP for 2 years on a stock ZZ3 350 bottom end with big chamber AFRs and a double thickness head gasket to get the compression lower.

You can get cometic MLS gaskets for LS1 in just about any thickness you want. I wouldn't do too thick, say over .070