We run a lot of them with girdles. We believe they help. I can say, I don't see how they can't hurt. Think about it, you stud the main caps and the tie them into a girdle that bolts to the oil pan rail. How can it not help? We have been running over 800hp with this setup for years. Bearings usually look really good when we do check ups. Only time they don't is usually with a repaired crank or where we have had other issues.
The weakness in aftermarket girdles is lack of height. Newer motors have deep sidewalls to tie into, adding a huge amount of stability up and down.
