I am not planning to race at all, just a daily driver for 100 miles running 80mph to 90mph constantly on a automatic. I want to get the most fuel efficiency and torque out of my ride and don't care about anything more than 4krpm.

Any suggestion? Is stock already designed for my purposes? I heard for low end there is no replacement for displacement but are there anything I can do? I have pumped 35 to my 14" tires and it seems like thats about it.

 

Underdrive Pulleys. That's your best bet for gaining a little more in the Lowend to Midrange. AEM is a good company to go with for Underdrive Pullies (AC/Alternator and Pwr Steering Pulley). The Pullies are lighter and bigger so its less drag on your engine therefore producing a little more power and torque.

 

Not much you can do except upping your displacement for low end torque.

a CAI, quality 4-2-1 header matted with a 2.25" exhaust system (that includes 2.25" highflow cat), will help a little bit, but the Cold Air Intake hump isn't until 4k.

Cams for your engine are all designed for higher RPM powerbands.

 

You could change your differential gearing by getting a new transmission, then you wouldn't have an automatic. And it'd eat up more fuel.

 

I am not really thinking about any chance of making my car unreliable or too expensive. I am planning to drive it till it break, and 40k per year is going to add up quick. I guess underdrive pulley, swapping motor, or swapping tranny is too much for my taste.

What about advancing the timing? Would it work well for low end, no differences, or worse?