I chose s15 since I don't own a s14 zanki or kouki and have a s15 front, my car was originally a 1995 rolling shell s14 so I suppose it was a zenki but no headlights came with it or fenders so... But the choice was simple, I owned a coupe prior not enough leg room or comfort for me and it felt unstable compared to my s14. I picked up the rolling shell for 800 bucks from DC back in mid 2006 and it has been a fun project. But main thing is comfort and stabability, I love how the coupes look but something about the s14 just seems right atleast for me.