The perforated is simply superior as it makes it so much easier to pass gas through those tiny holes. No more shifting your weight left or right while driving on the twisties. All you have to is relax, unclenched it and let it all go - let it go. However, you have to be very careful and not too relax because the holes are simply too tiny for solids.

If I am not mistaken, the non-perforated seats are the celica seats installed to spyders.. but I could be wrong.

 

Leather Seats

According to a Spyder buyers guide posting:

"In-so-far as I can determine, all Spyders delivered to the USA left the Toyota factory with fabric seat covers. Spyders sold with "leather" seats were fitted with them at the port of entry by the importers to increase profit ($800 in 2001). The exact design of "leather" seats seems to depend upon the importing company. In the SouthEast, the "leather" seats aren't entirely leather: Much of the seat cover is actually vinyl, or carpet. If you give the door-sticker coded information to your local Toyota dealer, they can tell you what seats your car had when it left the factory. "Leather" seats (even though they're mostly naugahyde) are highly prized."

So insert the word "perforation" for "exact design"...

 

I bought a set of new-in-box leather seat covers here on SC. They were identical to the seat covers I removed from my car (except not all smelly, cracked and ugly). Same interior markings, same construction. I have no idea where they were originally purchased but I assume from Toyota factory. ToyoDIY lists this, which leads me to think at least the perforated leather seats were a factory installed option.

71073-17350-E0 LEATHER SEAT, TAN, TRIM4*

To the OPs question, I'm not sure there's much difference in sweaty butt reduction with perforated seats vs solid. To detect difference between leather and vinyl is pretty hard now a days. The ultraleather, ultrasuede, alcantara fabrics are arguably better than cow's leather. The high quality (high price!) vinyls stay flexible in cold weather, are more UV resistant, less maintenance, and likely last significantly longer without cracking and splitting. Of course the vinyls don't have that unique leather smell.

 

I have a 2003 with leather seats, and they are perforated and the appear to be all leather (except maybe the backs). The original Window sticker shows the seats as part of the leather package that included the seats, door panels, and tan top. There isn't any indication if the car left the factory with the package or if it was added at the port of entry, but the car also has the "carbon fiber" dash kit, and I think that was installed at the port of entry.

 

the car also has the "carbon fiber" dash kit, and I think that was installed at the port of entry.

I've got the same thing on my 03, minus Tan top. also have said faux CF dash kit sticker pieces. Thought it was something the PO did to dress up the car. Interesting to know it's a Toyota option.

I'd be curious to know if someone knows where to get a passenger side perforated leather seat bottom covering. Mine has a tear in it.

Edit: wow, pricy $$ http://toyotaparts.checkeredflag.com/p/Toyota__/Seat-Cover/48861359/7107117300C0.html