My 4.6 seemed really weak when I got my truck and the gas mileage really sucked. The most noticeable power increases that I have gotten so far are from the intake and throttle body spacer. The intake got me about 15hp and a very noticeable four more miles to the gallon. The spacer added a lot of mid range torque, which has been really nice. Both mods are easy to install. As far as money is concerned, the intake is about 250 to 300 bucks and the spacer is about 100, but they have paid for themselves by now with the money saved on gas.

 

i have a suggestion for the mechanically inclined, spend $450 on ebay buy some 4.56s, new bearings, and crush sleeves. Install, you will beat the pants off your same truck with a tuner and 3.55s. Plus, no noticeable drop in mileage below 70mph.

 

No performance mod is going to drastically increase performance, unless you go forced induction or nitrous.

My personal opinion is, Don't waste your money on tuners, exhaust etc.

 

I had a '97 4.6L SC 4x4, auto, was totally anemic. I installed a bigger TB, intake, headers, chip, exhaust, and B&M tranny programmer just to make it barely adequate. I don't miss this pig at all.

Best bang for the buck, do the gears. 4.10 with 29-30.5", 4.56 with 30.6-32", 4.88" with 33-34", 5.13's with 35-36" This will give you the best power increase, might actually be enjoyable to drive.

 

do you know how much 4.88's cost? thanks

 

My cost for gearsetis approx $300Cdn each ($270usd), ADD IN $150cdn ($125usd) for a rebuild kit per diff, I'd say $2,100Cdn, or $1,800Usd for complete gear swap, lube/install included. Power difference, you can't get more for the price. I Swapped the sets in my current truck from 3.73 to 4.10, I wish I went lower.

 

lower you mean 4.56?

 

did you do the throttle body spacer yourself? is it an easy install? thanks

 

Honestly don't waste your time.
This get asked about twice a week: Does a throttle body spacer help?

The answer is always no.
There's even some posts with data.
It slowed one member down in the quarter.

Spacers work with carbs. They don't work on these trucks.

Search button is your friend

 

Actually, with a 4.6 the extra mid range torque from the throttle body spacer is really noticeable. The 5.4 has enough torque that it would be much less noticeable. Regardless, if you are going to get a spacer, then install it yourself. It’s really easy and only takes about thirty minutes.