|... General consensus seems to be the really big numbers belong to original low mileage examples, of which few are owned by members. That being said, everyone has noticed a slight uptick in values or the last few years... maybe on the order of 20% or so.
The discussion here usually ends up being about the value of a modded car and whether there is value added or subtracted by parts we have always thought of as upgrades.
My personal opinion, is its value added if (a) it's easily converted back to stock; and (b) its a simple understandable item. Mods like an aftermarket engine management system tend to be avoided by many buyers who see them as potentially expensive future repair costs.
The bottom line for most of us that we already have way more cash invested than we can expect to recoup, even with rising values. And that is OK with most, because its our hobby not a retirement portfolio. I bought a beater NA for under three thousand to save money and ended up spending nearly thirty grand... few here can get a worse return on their investment better than me.