Integra engine and Boost
 

How much boost on a daily basis can the LS and GSR engines handle if they had a block guard and a thicker head gasket? Can the LS engine handle much more than the GSR?

8 psi. The achilles heel of the engine is not the open deck or the cylinder sleeves- it's the rods and pistons. However, with a good sleeving job and forged rods and pistons, you can boost 12 psi pretty easy, more with good tuning.

If the engine is already out of the car, is replacing the rods and pistons something i could do my self? And isn't resleeving very expensive? The reason I ask this is that I'm trying to choose between the GSR or the LS engine to get. I'm thinking is i go with the ls the money i save can go toward building up the engine so later on i can go turbo. But if the Ls engine needs major rebuilding like resleeving(which is like 900$ right?) to handle decent boost then I'll just the Gsr engine and later put on a Jackson racing supercharger.

if the block is already out, replacing the rods and pistons are easier. if you have never done anything like this, i suggest you take it to a very reputable shop. resleeving the block and get a little pricey. look @ it this way..build the engine up, to handle more boost with a cheaper engine(LS), and be able to raise the boost past 8 psi, or buy an expensive engine(GSR), buy a charger, and buy the upgrade kit to boot between 9-11 pounds? your choice