only mods are vanes and hines exhaust , powercommander. did the fixes on the grounds except the one under the gas tank, did not do the desmoging or pair, the powercommander took away the backfiring out that was there at about 1/8 throttle ,tech said it was lean there . i adjusted the face panel buttons at the low settings but still have a slight surge , also loosned the cable ,tightned the intake boots ,did a smoke test around pipes for sucking air . is it normal for the black plugs theres only 4000 miles on it,put new plugs in ,there were black again. also i only get 28mpg the gas light comes on at only 78 to 80 miles i would appricate any feedback thankyou chet.