Sorry to come in late on the conversation.
Brad Mackey wrote:
Adam:
depending on the position of the pre-threaded holes in the seat, you can use the stock sliders by drilling a new hole in the top slider rail at the rear (usually).
The Kirkey's are a full aluminium seat. There are no bolts or holes in it, just a semi-flat aluminum bottom. You drill your own holes to match up with your mounting brackets.
When I put a Kirkey in my RX-7, I didn't use the sliders, but rather just bolted the seat in place, since I was going to be the only driver (and I wanted to maximize the headroom.
If headroom is not a consideration, I would just pull the sliders off of the stock seat and see if you can use the exisiting holes in the sliders and drill the Kirkey to fit. You may have to use some spacers up front if there is a gap between the seat bottom and the holes.
Perhaps as important - what are you using as a seat-back brace? The SCCA requires a back brace for these seats, and it may not pass tech without it. The I/O Port Racing brace is a fairly easy install if you have a harness or roll bar, but costs around $75 each.
IO Port also sells some side mounting brackets for the Kirkey's, but I'm not sure how this would work in a Miata - I imagine is depends on the seat width.
What model Kirkey did you get?
Good luck,
-bill