Not sure on details...he said him and his brother used to do it all the time on different fords...the only thing i remember was that id have to buy longer u-bolts.... his brother put a 6in custom on his bronco and it lasted heavy abuse for years until he wrecked it :/....

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99 Ford Ranger XLT 4x4 5-Speed manual, 6 cylinder 3.0
Dumped Magna Flow Single chamber
HP K&N Filter
Hurst Short throw shifter
Jet performance fuel injectors
12in alpine subwoofer, X-treme 600wat amp