speakers aren't what cause distortion at all
it's your head unit/amp gains
if you mean clarity, the sturdier the sub cone combined with a sufficient power source set on proper gains and a detailed box customized to the specs of the sub and a proper head unit RCA voltage and sub placement are what will get you no distortion

 

i'd try the new kicker cvt65.... a 6.5 sub.... it was designed to play sub frequenceys not mid bass
they like to be run free air.... we just got some in at my shop.... i want to play around then i'll tell you what i think of them..... if your close to a kicker dealer you should go check em out

 

4 pioneer interior speakers
alpine type-s sub box ported 10" sub
4alpine channel amp (interior)
1alpine channel amp (sub)

my setup isnt perfect but it pumps HARD!