I've had mine on for 3 months and i have noticed a difference. After i first put it on i started it and it sounded stock and i was about to cut it off then someone told me they take time to get loud. There are ways to make them loud without waiting like sparaying them with water when they're hot but i havn't tried that because it has been getting gradually louder. It also depends how often you drive it. I edon't drive it often so its going to take a while before mines at its loudest.

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2002 ford ranger 4.0 liter v6. auto. Cherry bomb glasspack dumped in front of rear tire. 33x12.5 Firestone Destination tires. 3'' Body Lift. Dixie Airhorns. LED's . Bed cover. Skyjacker fender flares. Blacked out lights, Hella offroad lights,camo seat covers,american racing wheels. HID fog lights and headlights.k&n cold air intake. bed cover.