I used the Predator from Diablosport, it's a handheld programmer. You can find these used for $250 shipped, they're $369 (new). With a programmer you eliminate the skip shift AND the 1-4 light. You could use the cheaper skip shift eliminator that plugs in at the trans but that does not get rid of the light.
The programmer comes with a "performance tune" - not much improvement, maybe 10HP... engine seems to run smoother though..... it does require 93 octane gas...
My '06 is a 6spd, I've used a Predator on my LS1 F-body with automatic transmission and it was a HUGE improvement just because of the changes made to shift points and firmness.