You could slap 6.0 heads on there and run more boost. It'll drop your CR to 8.5-6:1

You could easily run 10psi with that setup. The highest I've seen survive on the street is 14-15psi on a 5.3 with 6.0 heads. Remember with increased boost comes increased heat. The heat needs to be removed, so make sure your method of intercooling is up to snuff.

Oh yeah, Parish boosted the crap out of his stock 4.8. Something like 18lbs....it didn't like it either.

 

Ya, but I don't think he killed it though. Just pulled it to put his build motor back in. IIRC It made like almost 500 RWHP, but was spinning the tires on the dyno.

Jason from TSP made 500 rwhp with the STS kit he sold me at 18 pounds with the wastegate unplugged . The motor didn't break, but the trans did
And he said that was with the stock fuel system, even injectors, but he said he was spraying a ton of meth to make up for it.

 

brain fart....sorry

 

I'v been running 10psi for a while now. All stock 5.3 with injectors etc. Seems to be holding up fine, although I'm running a rich(~10.2 - 10.5) and only 15deg of timing.

 

10 is it I would say. I ran mine at 10-11 for a while without any problems. It was when I stepped up to 13 that I started having trouble. And the rings seem to be the weakest point for long term boost- for me anyway.

 

It's a 4.8. & my water injection isn't functioning yet. Wiring problem

 

i would run 8lbs of boost if you really want to be safe. with a good dyno tune it should last you a while.