A gear swap doesn't have to cost $1000.

That's why I asked what gears he's running now and if he's 4x4 or not.

He might be able to get a junkyard axle with the 3.92's for a few hundred bucks and then sell his current axle for a few hundred bucks and do a "free" gear swap if you don't count his time. No need to tear into the rear end that way.

There's a pretty good seat of the pants difference between a set of 3.55's and 3.92's. Maybe not much actual 1/4 mile difference, but for around town I can notice a good difference driving a Dak with the same motor and tranny but different gears.

 

Getting a bigger throttle body isn't going to allow for much improvement if you don't get a better exhaust system. You can only pull in as much air as you're pushing out.

I've currently got a custom 93 octane tune from Hemifever for my 5.7 with 3.92s and holy cow did it make an improvement! If you have 3.55s, you're not going to feel a whole lot of improvement, but there will still be an improvement.

 

He said he was getting headers so I would assume he would be doing a whole exhaust. Hey you never know tho

 

I've learned to not assume anything. Ever.