Definitely all the 90s JDM is being driven by our generation (Gen X/Y) because we either had 1 back then, or lusted after them and couldn't afford them. I'm glad I jumped on an FD RX-7 in 2010. As you know I got the Stagea a year and half ago and they have gone up also!
I find with S30Z's they have a rally or surge in value, then plateau for a bit, maybe go a little backwards for a bit, then they surge upwards again.
I got my red 240z back from @C.A.F. the other weekend and I must say I missed it. They are so mechanical and raw. As much as I love the RX-7 and Rb26 Stagea. Something about the rawness of older cars that cannot be replicated today.