Royal: As per pretty much what Justin says, they have a close ratio 6 speed box as well which makes driving a spec R a lot different. The initial kick you get off the turbo is very sudden, you'll get full boost earlier however it runs out of puff before you hit the limiter!
I've gotta be honest I never did a lot of research on one technically, in all seriousness it is only a revised S14(a), it was the look of the thing that originally attracted me. It's definitely the most comfortable car I've ever driven, I could drive hundreds of miles and still feel fresh when I stepped out at the other end.
Chassis wise all I actually know of is stiffer springs! lol! I had S14 coilovers on mine! Some came with hicas, mine didn't however. The diff is really nice to drive with, it will lock suddenly but it's also very predictable. I found it spot on fo beginners drifting at TrampDrift.
Big gay wings were optional extra
S13/14's feel slightly dated these days I find, an S15 feels like a very modern car!
I agree 100% with Clarkey on the price however, they are still raking in the JDM tax, I have no regret about spending 10k on one though, I loved every minute! If it makes you smile, it's worth the money - simple as!