Well... they are plastic. Wouldn't hurt to slot the mount holes on the one in front of the washer tank and then add some washers on the other one to space it out some

 

I’d have to cheat that panel out nearly a 1/2”, which would bring up other issues that would be worse.

 

Maybe the car's unibody slightly arcs with time.

 

Current JDM FD on BAT atm has a pic of the carpet. Short gap may be for the optional parcel strap to pass through.

https://bringatrailer.com/listing/19...da-efini-rx-7/

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Just took a look at my car this afternoon.

I have spare tire, spare tire cover, 1/2 sound deadening over lay, then the '99 speak carpet. Also the end trim is NOS, so all the backing foam is new. I have the washer bottle.





The 1999 spec is much more lightweight than USDM s6. I think yours may have indeed shrunk. Perhaps your solution is to by a JDM replacement.

 

Finally remembered to snap a couple pics of my GA hatch mat when I was at the shop. FWIW….