Review on High-Quality ARP 912-0011 11mm x 2.00 Thread Cleaning Tap: A Must-Have for Precision Thread Maintenance by Justin Cage

This tool works very well. You'll be surprised how much crap you can pull out of these holes. I strongly recommend protecting the cylinders and cooler bags from dirt. I use this tool in conjunction with a brake cleaner. With LS engines it is very important that they are clean or the screws are hydraulic. Spend your money on the right tool and get it done before you try to break your head.