No, several guys on here have put 317 heads on 5.3 boosted motors to drop the compression.

 

sweet!

 

I've seen as high as 14psi run on a bone stock 5.3 with 180k miles on it with no issues. The proper tune, fueling, and intercooler and it can be done. Especially if you drop the compression with 317 heads. With stock compression meth injection would probably be required for much over 12psi.

 

I would run a 60 to 67mm turbo. depends on cam and CR

 

Make sure you get a 0.81 A/R or smaller exhaust housing too.

 

.68a/r is the way to go for the 4.8, and exhaust wrap from headers back