[Nagakilo]

This summer I have my little car budget and I was looking at putting in a BBK Cold Air, and potentially some gears. I have an 04 6-Cylinder. Only performance mod on it is a single flowmaster muffler swap. Now, here is where the question is. What kind of gearing would be best for a 6, and are their any risks involved in running different gearing? Is it gonna kill my Fuel Mileage, burn up anything in the engine, etc.? Mind you I have an automatic trans. I really don't know much about gearing, so I'll have that professionally installed, so if you have you could use "stupid words" for the explanation I'd appreciate it

EDIT: Oh or if you have any suggestions for a better cheap upgrade instead of the gears. I'm looking at a 300$ budget and the Cold Air is $140 if I recall right.

[stlwagon]

A set of 3.73 gears would wake that up without costing you too much at the pump. Would just need to adjust your speedometer.

[BKid]

Gears installed would be around 700.00

[.boB]

There's really no such thing as a "best" gear, unless the car is used for one specific purpose. Lower the ratio and it will run better around town, and turn better times on the quarter mile. But then you'll turn higher rpm's on the highway and get worse fuel mileage. And your lap times on a road course might suffer. It's a big trade off.

Since you have an automatic, try this. Every time you start the car, turn the OD off. Only drive with the first three gears - no OD. Take note of how the engine sounds, what your rpm's are, and what your gas mileage is. That's about/roughly what will happen at the top end with a significantly lower rear gear. If that works out, then consider adding a 3.73 gear.