hey all i have 2002 screw with mac 75mm throttle body and port and polish tb elbow underdrive pullies k@n fipk cold air mac si/so 3in catback and 6600 every thing works good but im runing 9.75 5.4 355 Ls if i put 4.10 in would it be to much some time down the road i do plan on buying 21 or23 ft trailer i know ill have to get my 6600 reflashed no big deal thanks 72 mustang

 

Not too much ! Many members here have done the exact same swap. You'll be a happy camper ! I did similar mods on my last truck. I installed e-fans and a shift kit to round things off.