there were two different spoilers for the 6th gen coupe.
this one
and this one
if you are looking to get the second one, jst get the oem spoiler made for the 7th gen coupe, looks similar.
if you are looking at the 1st one, then one commeonly referred to as the Si spoiler, it would be about the same width, i just dont know if the body lines would match up.
the width is about 67 inches on both cars. and im sure the trunks are pretty similar also.