The lower grille mod is exactly what Dulvalius said. It only works for the Roto-Fab style intakes. I believe you can do it to the stock intake set-up, but you also have to do the lower panel mod to go with it....or it will be useless. Once cut, it will act like a ram-air style.
I really dont have enough miles on this new setup to really tell yet if I have better mileage or not. I will have to monitor it over the next week or so.
: 2009.5 SBM G8 GT, Premium Package, Sunroof, Pat G. ECM/TCM Tune, Roto-Fab 102mm CAI, LS7/LS3 MAF, Kooks 1 7/8" LT's, SOLO HFC's, SOLO Mach-Shorty Balanced Catback, SOLO 3.5" Tips, 19" Sport Package Wheels, GXP Steering Wheel, GXP Diffuser, Neondials, VG Sharkfin II, Debadged (Except Arrowheads), Hood-Vent Mod, Lower Grille Mod
: RCR Modified Intake Manifold, RCR Ported TB, Powerbond UDP, Suspension Upgrades