The L81 in the Catera is the X30XE in the Omega. Same engine different name. The L81 uses a "G" intake cam and an "A" exhaust cam. For a write-up on an upgraded V6 with up to 250 HP using Catera, CTS, Saab, parts including those "G" cams go to:
http://cateraowners.forumotion.com/t521-build-a-catera-performance-v6-240-to-250-hp