I was wondering what gears in an ATX neon need to be changed to lower the ratio?

 

It would be the differential (Final Drive Gear). The gear that actually turns your axels.

 

Also, reading this and seeing all the fighting over which engine is better, a DOHC or SOHC is ridiculous. Besides the shape of the intake manifold ports which can be modified easily with a dremel and a steady hand would be the cam. The difference in the lift/duration/seperation of the cam lobes is where the difference in the torque curves come from. Taking the cam and any other changeable parts out of the equation (seeing as you can have cams made to whatever specs you want from a good, reliable machine shop).....
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the ONLY TRUE advantage any DOHC motor design has over any SOHC motor design is the ability to adjust the intake and exhaust cams separate from each other with adjustable cam gears.

Mopar has even made that almost obsolete with their constantly varying camshafts they put in the modern HEMI motors that can change the intake and exhaust lobe separation by up to 40 degrees while driving on a single camshaft. They have also dabbed in the camless engines using computer controlled solenoids to activate the valves individually allowing them to open and close as far and as fast as needed.