Have $700 to spend, need opinions.

700 could buy you a used vortech head unit

Gears and tuner FTW! Thats what I would do really. 4.10's are nice but I drove alot of hwy miles with mine and gas mileage sucked ass. Also makes it a bit of a beast to launch. If I were in your shoes I would go with 3.73 and tuner. You WON'T be sorry! Great SOTP gain there

700 jr. bacon cheeseburgers



















3.73's (free right?), and a sick tuner with logging abilities

If the 3.73's are free, get them. 4.10's are better for an auto since the auto gears in the transmission are numerically lower. Plus it will save you what..169-189 dollars?
I would buy underdrive pullies, a CAI, mass air flow and the tuner. The 4.6L is very responsive stock. With those few mods combined...it will wake it up a little bit more, and under the hood will look better with the CAI than a stock rubber tube and plastic box.

If you don't like that. Buy some BBK long tubes and matching H-pipe. That will eat up most of your cash, but if you can do it yourself, you will save yourself at least 400-500 bucks in labor. (Just make sure your clutch and transmission are in good shape before you put the L/T's on.