[Aaron]

Sims,
I have no idead about some of the junk posted in those threads but here's basically info on the RX7 caliper idea..

1. You need to either grind the rotor channel about 3mm wider OR put a 3mm spacer in the bridge of the caliper. The spacer needs to be flat alloy with 9mm round 1mm deep seal groove cut in plus associated through holes etc. You'll need new bridge bolts and pad pins etc. Grinding is the easy way out but does mean you'd meen to shave the pads a little as well.
The metal you're removing isn't strictly structural so it's up to decide which is more acceptable. Either that or find a 22mm thick rotor of about 295-300mm which is the largest diameter the rx7 caliper can grab effectively (supposedly 314mm is the max) There are plenty of 24 and 25mm thick options.

2. The setup described runs custom - or "odd" hats to mount the rotor. I never did see an actual rotor height measurement anywhere. This is the most critical measure as it would then tell us more about how the caliper is mounted. But in general the caliper mounting is pretty close, a few mm here or there really.

3. Wheel Spacers were needed due to the rim design in use. You need ~65mm from rotor face to inside of wheel spoke MINIMUM.

4. The caliper mounts have never been well described, although in theory the caliper will pretty much bolt up the factory knuckle and support a 295/300mm rotor. Some spacing my be needed. Also through bolts will need to be used as the knuckles aren't threaded and neither are the calipers. However given the choice of threading alloy or threading Cast steel you'd thread the steel, or use a relcoation bracket to get things spaced and bolted up 100% perfect. Elongating mounting holes is a dumb practice when it comes to brakes.

As for Cost - if you take $2K to a brake specialist you'll get a great setup with PBR calipers and very few clearance hassles. Plus all gear is new and properly engineered.

If you DIY then you're up for:
* RX7 Calipers (about $250 pair + rebuild)
* Grinding or bridging calipers (unless you use a 22 thick disc)
* Mounting points - probably fabricating locating brackets etc etc
* Rotors at say $250 pair
* Rotor hats $$$$
* Pads

etc etc

It's possible and at the moment at least two people on the forum are working on Big setups using RX7 calipers, but keep in mind after 8 months of research and measuring it's only just getting to the point of bolting stuff together.

All in all you could look at the following ideas that would be easier:

* Use Millenia or Subaru twin spot calipers
* Get new rotors and great pads then re-visit the idea of getting bigger brakes if you can't stop the car after that.
* Pay $2K to get a Professional to do it

Factor about the same to do the rears - although there's plenty of 280-314mm options availbe from Mazda that could be bolted up.

If you've got 4-stud you probably could forget it unless you really want to invest in 5 stud conversions (another $1K plus wheels)

A.