im a chevy guy and know how they do with certain changes but a buddy of mine has a 2005 ex.cab short bed f-150 fx4 with the 5.4 i had him get the corsa cat back and the edge programmer and he alresy had a intake BUT he recently got 305-60-18's for his truck so i told him to get better performance he should upgrade to 4.10's and a true trac ....i believe he has 3.73's now is this good advise ????????i know its a graet setup for a silverado but is it the right one for his heavy f150????? its a dd and he tows with it but is also on the highway aswell its gonna cost about 1300-1500 bucks is the performance gonna be worth the price???? thanx
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IMO the gear jump from 3.73's to 4.10's isn't worth it. Those are only a 33" tire so he should be just fine with 3.73's

 

it is really not worth getting 4.10s. he isn't going to gain that much power back and his gas mileage will decrease