I have the ones made by CATZ and love them..they are extremely bright at night, and they don't light up the entire brake light encasing, all you see are thest 2 quarter size(a bit bigger) red dots...looks good i think.
yeah they doo make you signal blink fast.
but i think that looks good too, as long as you can deal with the fast clicking sound.
the reason they blink fast is that the LED lights have a low resistance...just like when one of the filaments blows out of a dual filament bulb, so the car this the bulb is blow when it actually isn't
if your gonna get them just make sure you pay a little extra and get a good brand.
cause the cheap ones aren't as bright, and you can't see them that good during the day.
I like the CATZ ones or the EuroLite ones the best.