Currently have 2000 F150 with 4.6l and 3.55 axle. Truck is pretty sluggish. Will going to 5.4 alone be sufficient or should I also go with 3.73 axle. I do not want to suffer when highway driving.

 

I have a 2001 with a 5.4 and 3.55's and I'm happy with the performance. It all depends on if you do alot of towing or not, if you tow alot you might want to go with the 3.73's. It'll make your engine run a little higher but it shouldn't be too much.I would definitely go with the 5.4 though, you won't be disapointed.