There are some undeniable perks to being on the taller side—reaching the top shelf without a struggle, flat-footing most motorcycles, and effortlessly spotting your way through a crowd. However, squeezing into a small Japanese roadster? Not one of them.
At 6’2” with a weightier build, I appreciate that the NC is the largest of the Miatae, but "spacious" still isn’t the word I’d use to describe it. It’s certainly more accommodating than an ND, but every extra bit of room is a welcome improvement. So, after getting accustomed to the NC, it was time to break out the angle grinder and see if I could uncover a few extra millimeters hidden within its snug interior. First stop: the OEM heated leather seat:
I don’t have any major complaints about the NC2’s seat design. It provides just enough bolstering to keep my larger frame relatively secure while tossing the car around, without feeling overly restrictive. Because of that, I’m hesitant to swap them out for something more race-inspired—especially if it means sacrificing comfort and walking like Quasimodo after a long drive.
There’s a rumor that early NC1 models without height-adjustable seats offer nearly an extra inch of headroom. While I wouldn’t mind a lower OEM seat, modifying the stock one lets me save some cash while keeping the all-important seat heaters for those occasional winter drives.
For reasons unknown, Mazda decided to add “seat risers” to the 2008+ height-adjustable NC seats. I’m sure some engineer out there could explain the logic behind it, but after looking at the design and clearances, I was left scratching my head.
Removing the stock seat is a straightforward process—just remove the four bolts securing it to the floor, disconnect the single wiring harness, and it lifts out with ease.
With the seat flipped over, the four bolts attaching the seat pan to the frame are clearly visible:
A closer look at the mounting points reveals where Mazda decided to add the aforementioned "seat risers"—essentially an encapsulated nut welded to a thin metal plate, creating additional space by raising the seat pan slightly.
Interestingly, the encapsulated nut is oversized for the bolt it holds—the bolt doesn’t actually thread into it. It’s simply being used as a spacer. Now comes the fun part—breaking out my favorite tool of all time. The tool that only sees the light of day when patience runs out and irreversible decisions are about to be made—the angle grinder.
A few minutes later, all four spacers have been lopped off, now lying lifeless on the floor. That'll teach them to... well, whatever it was they were supposed to be doing.
Yeah, I get it—jumping straight to destructive, irreversible modifications to OEM parts might seem a bit extreme. But if I ever change my mind in the future (which is unlikely), it wouldn’t be too hard to add washers or a solid spacer back to the mount to raise the seat pan again.
I’ve also heard of people rotating the mounts 180 degrees (since they swivel easily) and placing them on top of the seat pan to gain even more clearance, and the best part is, it’s completely reversible. Rumor has it that method can add 1 to 1.5 inches of extra headroom, though I wasn’t sure I really needed that much. But, let’s be honest with ourselves—I just couldn’t resist the opportunity to fire up the angle grinder!
So, how much extra room did removing the spacer actually add? I grabbed my trusty calipers, and after just a few minutes of cutting, I gained just over 10mm of additional headroom. Not a huge amount, but hey, progress is progress!
I’d like to say this entire venture was free, but instead of using washers to space the OEM bolts, I made a quick trip to the hardware store and picked up four M8-1.25 x 20 flanged bolts to ensure a perfect fit.
It’s important to note that this modification doesn’t lower the entire seat—just the seat pan. This creates a small gap between the seat bottom and the seat back, which isn’t noticeable when you’re getting in and out of the car. However, it does change the way your back engages with the seat slightly. This is also why I didn’t want to lower the seat pan too much, as it would affect the position of the OEM lumbar support.
In addition to the extra headroom, I noticed a slight improvement in legroom as well. My guess is that the gap between the seat pan and seat back lets my hips slide a little further back, giving just a bit more space for my legs.
Speaking of the seat back, I’m not a huge fan of the non-adjustable lumbar support in the OEM seats—it tends to push my hips forward a little. So, while I had the seat apart, I figured it was a good time to modify the seat shape to better suit my preferences.
Removing the lower portion of the seat cover is pretty straightforward. On the back of the seat, there’s a folded plastic piece holding the cover in place. Pop it out, and you’ll expose the bottoms of two zippers that need to be undone to loosen the leather (in this case) seat cover.
To pull the front of the seat cover up, you'll need to remove the hog rings that secure the cover to the frame of the cushion. They're easy to open with a thin set of pliers—or any tool of your choice. Since I was only trying to access the lower portion of the seat back, I removed just the lower set of hog rings. This allowed me to lift the cover high enough to get to work.
Since my Grand Touring-trimmed NC has heated seats, the seat heaters are simply attached to the foam cushion with a light adhesive. All that's needed is a gentle pull on the seat heater pad, and it slides up with ease.
Since I wasn’t trying to completely reshape the seat, only adjust it to my liking, I used a surform tool to file down the areas I wanted. This helped create a more comfortable seating position for my frame.
I was hesitant to shave too much off the seat cushion, as this isn’t something that can be easily reversed. However, I did manage to remove just a bit of the extra lumbar support, which ever so slightly gained me an extra millimeter or two of legroom while improving the feel of the seat for my body type.
That said, I only performed a mild shave. To those that are a bit more bold, this job could be easily done with an oscillating tool to sand it down a bit more foam in quite a bit less time.
With all the shaving, cutting, and grinding, I got a little carried away. I figured while I was at it, I might as well focus on the throttle pedal for some extra legroom, specifically for my right leg.
Removing the OEM throttle pedal is a quick task—just two bolts securing it to the chassis and a single wiring harness plug.
My plan was to trim a few more millimeters off the back of the pedal mounts to bring the pedal closer to the floor. The problem, though, was that there wasn’t much material to remove… but that didn’t stop me from grabbing the angle grinder and giving it a go!
In the end, I managed to remove about 1-2mm of material from the pedal mounts. The result? The rear of the pedal assembly looks like a half-melted monstrosity!
Luckily, that portion of the pedal isn't really visible when you're sitting inside the cabin.
In hindsight, I didn’t notice enough of a difference after grinding down the pedal mount to recommend the effort to anyone else.
With my thirst for grinding finally satisfied, everything bolted back into place with ease, and it looked as though it came straight from the factory.
Overall, this wasn’t a bad way to spend a couple of hours. A quick drive revealed that the interior space had indeed improved. My hair no longer brushed the soft top, and my legs could stretch out just a bit further— all without spending any of my hard-earned money (minus the cost of the four bolts for the seat pan, but let’s not get bogged down by the small stuff).
I drove the car around like this for a few days, appreciating the improvement but still wishing for just a bit less lumbar support.
I came across a post on Miata.net where someone claimed they removed the rear seat springs, drilled new holes in the seat frame, and gained an extra inch of legroom. I’m not sure if they were working with an early NC1 or if I was missing something, but my caveman brain couldn’t quite see how that would work. Then, inspiration struck: Mongo smash.
On the back of the 2008+ seats, there are only two springs positioned in the lower back/lumbar area, pulled fairly tight against the rear of the seat cushion. Accessing them is incredibly easy—it only takes a few seconds to slide the seat forward and unzip the seat cover.
Upon seeing this simple spring arrangement, I did the only rational thing that came to mind—I yanked on them like a toddler throwing a tantrum in a toy store. Voila. Within seconds, the springs were noticeably looser, no longer pulled taut against the rear seat cushion.
How loose, you ask? Well, I stretched them to the point where they now pull away from the seat cushion effortlessly—with just one finger.
The result? That pesky lumbar support that used to shove my hips and lower back forward is now completely gone. To overuse an old, tired cliché—I finally feel like I’m sitting in the seat, not on it. As a bonus, I even gained a dollop of extra legroom for my troubles.
All for free, in just a few seconds of my time. All I had to do was yank on those springs like a raccoon trying to break into a locked trash can.
All in all, Project Tall Man in a Small Car was a success—but it’s just the beginning. Now that I've got a little more space, who knows what I’ll tinker with next? Maybe I'll start eyeing other areas that could use a little extra room. Stay tuned for more grinding, filing, and the never-ending quest for a little more comfort in a very small car.
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