The lower grill mod is when you take off the lower drivers side grill and shave the backing off the side nearest to the fog light. It lets more air through that port and air goes directly to the cabin where the air filter sits.
2004 Turbo Cavalier Arrival Metallic Blue- @ 12 psi SOLD!
2012 Jeep Grand Cherokee overland Daily Driver
2008 G8 liquid red - rotofab, stainless steel 1 3/4 long tube headers, solo mach shorty balance catback, spectre 4" maf housing and LS3 maf card, rcr spec'ed cam (219/227, 604/614 113+1), dod delete kit, yank ss3600 stall, prc heads (ported/polished/milled .035), pat g tuned. 3.45 rear diff.