I agree that aftermarket rods are an overall better option, however this is how you can remove the OEM press-fit rods without breaking the pistons.

 

Futral motorsports in Walker LA.

 

I tried something similar to that and they shattered.

 

Allan Futral has a solid reputation around here. Several close acquaintances that are happy customers.

 

GM has a dealer tool made just for changing pressed in rods. I used it alot .

 

on sbc's i used a propane torch. dunno I'd mess with one on an ls though. so much less meat in the pin boss it'd be easy to hot spot it.
yup GM has a special tool, or a reasonable machine shop has a rod oven.
I got quoted $60 for a piston swap, but I ended up with floaters in the end.