Originally Posted by usaweapon777
Also when looking for silverado's with the vortech car craft says to avoid the cast # 10239906. It has hardened exhaust seats that limit flow supposedly. If anyone can validate this info that would be great.
This Info has been debunked. Some of these have a small lip where the Seats were installed, if so it's easily removed. Hardened Seats are a ++ to me.