I went with FLASC for my Phenom. No port control bore, with porting with the 2" and 3" extension.
No complaints really. Would like counter threading for the tips, but that would effect the extension
Quick fix is just add a few layers of teflon tape to the threads. I did it with the 2" extension, so it wouldnt unscrew out of the silencer/mg shroud when changing the control bore.