just my 1 cent & im by no means an expert. the cams fine for an A4 auto w a stall. could have idle trouble w/o stall. with a better cam good springs are a must plus tune. i would check with texas speed or your local speed shop if the heads your choosing will fit. i think i remember a slightly diff head bolt pattern for the 98's ??? im happy with my ls6 intake but if you plan to rev past 6 grand i'd think about the fast 90/90. again, just my 1 cent ps i got my ls6 cast#243 heads from texas speed.
99 Z28 vert "florida" orange , acquired 9-03 A4, slp lid & cai, safety loop, bmr sfc, lca's & panh, edelbrock rpm catback w/chrome stock tips. ls6 heads & cam & intake, 80mm tb, jet hot LT's, drm tune. gforce comp 2's. newly added slp 85mm maf, ud pulley, alum ds.