did mine the other day, i have cobra daytonas fitted in a cup....... To remove O.E seats you will need deep 13mm socket, 8mm (for battery), trolly jack and axel stands maybe some wire cutters....and some torx bits
1. Disconnect battery
2. jack up car. Starting from the passenger side underneath there are two rubber plugs (approx 25mm in size) pull them off. These are the seat bolts nearest the doors.
3. there are two bolts left for the runners near the hand brake, these are situated under the exhaust heat sheild after the cat. Remove the sheild, (think its a torx bit) you will now see two nuts, undo these, seat will now be free
4. before the seat comes out you need to disconnect the pre tentioners, on mine i had to cut the wire as it had been soldered on a reno recall, but some have a plug i beleive... disconnect however appropriate
5. pull out seat, be very carfull NOT to catch the sill.... thats removing them pretty much, i had reclining subframes to go back in, and that is pretty much the reverse of taking them out, i had to strip the pretentioners off my original seats to put on the cobra subfames, but if your using harnesses i beleive you can do away with these
its not too hard