i was told i would burn way more gas or run lean???? this would be due to more air flow and the car senses that and uses more or less gas. or could run lean without a tune....???

 

No.... Dude stop worrying about it.

Adding headers will increase your MPG just a tad. This is because the engine can more effectively remove exhaust gasses. This reduced load is also the cause of the increased HP.

 

With matters such as this, you don't need to worry as much. Many people have installed headers with great success. With something as thoroughly tested within the community, you've got a safe bet.

 

has anyone found the bolt sizes for the headers? the ones that screw into the block?