I was told you gain a little with smaller tires but lose a little top end. Whats the smallest size i could go on stock wheels?

 

Yes that's true, you would gain a little. You could put rubber bands on it, but then you've entered the "rice" zone and will get disowned here!
What size tires do you have now? You can figure the math yourself, as long as you know your rear gear ratio.
Say you wanted to figure what your RPM's would be in any given gear. The formula is:
mph x trans gear ratio x rear gear ratio x 336. Then take that answer and divide your tire diameter into it.
Tirerack.com is a good source for info. Look up your tire specs, and it will give you tire diameter, width, rev's per mile, etc.

 

Well theyll be on the stock rims anyways so it wont look like a rice burner.. itll look original just the tires will just be small.. Anyone?

 

Anyone? Did you glaze over my last sentence? ^
Maybe my response wasn't clear? You can look up Any Tire they carry and check ALL the available sizes for height comparison.
You can go with as small a diameter you want, within reason. Simple answer is you can put on the smallest tire they make to fit your wheel diameter.
Just keep ground clearance in mind, as it will be dropping the car down. And a smaller dia. tire will also give you more fender clearance. Too much fender clearance won't look good.