NA Miata Booster Delete Help

Bonjour Grassroots. Been reading this forum since the beginning of time, didn't sign up till today.

I've driven many many many vehicles in my time, and to my surprise, have fallen in love with an NA Miata. I have now been daily-ing it for two years.

I always end up finding what I need on this forum, rather than a dedicated Miata forum, so here I am.

Looking for advice on how to properly delete my booster. Yes, this is a street car, and I want to delete the booster. I hate boosters. I hate how they affect the feel of the brake pedal. I hate boosters the same way I hate power steering and clutch springs. This is not a show car, I do not plan to plumb my clutch master into the brake reservoir to "shave" my engine bay :facepalm:.

In the process, I want to install a proper twin master cylinder setup with a balance bar. OEM brake design always bothered me, I've dealt with multiple brake pressure loss failures and want dual cylinders.

I know CompBrake in the UK makes a bolt in pedal box to the factory firewall holes that increases the pedal ratio from what I believe to be 4.:1 to 5:1. Is that enough? I've seen where someone drilled the attachment point on the pedal arm higher to get more pedal ratio. Not sure I like the idea of applying pressure on a angle like that directly into the master cylinder, but if using the pedal box I don't see why that cannot be done to increase the ratio.

CompBrake Miata Page: https://www.compbrake.com/product-category/cars/mazda/mx5/

I also know that the Miata's booster pattern is shared among many other Japanese brands, so I'm sure there are other options, have yet to find them though. I think it might be necessary to increase the pedal ratio more?

Car is an NA6, will up upgrading to NA8 brackets, rotors, and pads. Undecided on pads. I can't go bigger on the brakes, future wheels won't allow it.

Since I'll be splitting the front and rear brakes with two master cylinders, what diameter bore should I be looking for? Of course, taking into consideration there will also be no more booster. I understand I need to size down to decrease pedal effort.

If the right parts are chosen and this is done right  I see no reason why this setup can't be street-able.

Any help greatly appreciated. :)

The Compbrake setup looks nice, although when I was looking into it a while back, somewhere I got the idea that the pedal ratio was off.

For manual brakes you generally want a roughly 7:1 ratio.  I have not measured a Miata, but I did measure an RX-7 (0th gen Miata) and found a 4.5:1 ratio.  I redrilled the hole in the pedal 25mm higher to make a 7:1 ratio.  (I'd like to say the pedal was 315mm long, the stock pickup was 70mm from the pivot  and I redrilled it to 45mm)

Wilwood makes a NEAT little balance bar that incorporates a 1.6:1 ish leverage ratio, so you can use a power brake optimized pedal with no redrilling.

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It will be more expensive than the UK kit ans will require fabbing, though.

Incidentally, since 1968 in the US (and probably Canada since Canadian DOT largely follows US regs), all cars sold have two master cylinders.  The pistons are in series in one unit, but they are two separate units. Failure of one circuit will have the same pedal behavior no matter if the masters are in series or parallel:  Very long pedal travel until the dead circuit's master is bottomed out, and then the good circuit may get pedal force.