an OEM replacement, given that the motor and PCM are bone stock?

Are the only differences the build quality and tolerences?

Are they just more reliable or do they offer a performance advantage?

Again, given that everything is bone stock.

 

Won't be a performance advantage, but they are built better and 'should' last longer

 

There is the pro billet that has a different way of working that is better and you can adjust the timing on it. The life span and reliability is better from what im seeing.

 

It is considered a direct replacement for stock. They have had numerous quality issues that hopefully have been resolved. Only time will tell if they are indeed better that a GM unit. I don't think enough have been in service long enough to judge that just yet.