Anyone know if the JDM Bilsteins that came on some later model FD's like Spirit-R Etc. are the same or different valving as the aftermarket HD Bilstein's?

 

Try contacting "laujesse"

The actual Spirit R sales brochure (in Japanese) probably gives a description of the Bilsteins. But I suspect they would not give a reference to the Bilstein factory comparable.

The Japanese service manuals updates have quite a long discussion about the bilsteins (if I remember correctly). In Japanese.

 

 

The bilsteins came in several flavours on the various models, there wasn't a singular type, they did come with the mazda and bilstein part numbers stamped on the body, weren't HD. Uniformly they were mostly bad - the do have a tendency to ride the bumpstops on anything less than marble smooth....and when you see the humongous size of them you can understand why! If re-valved, normal bumpstops and adjustable seats installed, they're excellent.