What would be the gains and sacrifices of slapping these heads on my motor??

I know i would lose a little power but where at exactly? if i get them milled down.. could i get any gains since i'm actually boosting compression ratio? or should i just keep them for when i go to a 5.7L?

 

you'll actually lower your comp ratio

 

This has been covvered a few times in recent weeks. The larger combustion chamber will effectively lower your CR, costing you power. I don't recall how much you'd have to mill to make it worthy, if possible.

 

hmmm... maybe i should get financed for a sts turbo then?

 

I just dont understand why everyone who has a 5.3L i ask this question to wants to buy them off me?.... even performance shops are asking if i would be interested in letting them go... I know there descent good bare casting heads thats a no brainer...

 

243 heads work great on engines setup for the larger CC. My heads are 799 (same as 243) and they work well with the flat top pistons in the L33. They are an upgrade for the LS1 so most would want them.

 

myy 07 nnbs with a 4.8 has 243 castings from the factory.