i polished the inside of both my MAF's with no problem all i did was take some 1500 and 2000 grit sand paper and smooth out the roughness have not had a problem with either of them did the same to the throttle body too

98.5 Black SE ATX S&B filter, SVT MAF, optimized SVT TB, mesh grille, removed orange reflectors, painted rear reflector, gutted pre-cats, optimized SVT LIM, 19lb injectors, resonator removed cant afford an svt but lookin for 1 in nc