I need to know because I want more top end.

 

I'm confused. What do you mean by this? Top end speed? Are you hitting redline in 5th, or something? That's nucking futs. If you mean top end power, then you're just high. Changing gear ratios won't give you any power. Going to a lower (numerically higher) ratio will give you better accelleration and lower gas mileage, while theoretically impacting the top speed the vehicle is capable of achieving if it had the power. That's a big if.

To answer your question, most 2nd gens had the 4.1 final drive ratio. Automatics and early 'verts had 3.909 gears. And only the GTU-S got the preferable 4.3 gears. You can even get 4.88 gears for a 1st gen, but you have to get a real good welder to extend the pinion shaft.

 

This should answer your base question http://www.mazdatrix.com/g5.htm