The s14/15s have a broader power band due to the vtc. There are also almost always much cleaner than any s13 engine that comes in just because they are almost always so much newer even then most of the s13 blacktops.

It is a little trickier to get some of the parts like manifolds and cams, but otherwise its the same. Right now we have s14 cams in stock as well as several other s14 parts.

I personally think its worth the extra money if you can spare it, but thats just me