Mazdaspeed Style NC Underbody Brace Kit

Installed this on my new to me 2014 MX-5, primarily because I wanted more support for the rear subframe. When it arrived I'll admit I thought Good-Win-Racing had sent me an empty box, or perhaps a set of floor mats. The braces are very light, probably weighing less than the factory parts they replace.
Installation was straightforward as I was using a lift and was able to keep the chassis level. I started at the rear, working forward keeping everything loose until all bolts were inserterd. I would caution you to chase out all bolts and use a torque wrench. This includes the threaded holes on the brace itself. I did not have to notch or cut anything as some others did, the included spacers allowed adequate clearance where needed.
My car did not have noticible squeeks or rattles prior to install, but I did notice a decrease in NVH immediately. The rear feels better planted, so overall I suggest this modification.

-- Cullen R. ( 2014 PHRT Club AT ) May 2026

I just installed the Mazda speed kit from GWR on our 2011 GT PRHT. I used the pics included on the product page. I did have to grind off the edge of the factory brace that is located under the tranny. I held up the new brace with a couple of bolts and traced area to be removed with a sharpe. No big deal with an angle grinder. Hit it with some rustoleum black paint and good to go. Left all the bolts loose until I had all threaded into place. Assembly went together in about 2-3 hours but I work slow laying on my back on the garage floor. I already had the car up on Jack stands to do fluid changes. Driving the car this afternoon on a quick test and the whole car seems tighter. Also took out some rattles. Happy with the outcome!

-- Steve W., Salt Lake City ( MX5 2011 GT PRHT 6MT ) January 2026

Noticeably helped stiffen up the rear of the car over bumps and rough pavement.
It feels like there's more motion being damped by the shocks rather than going into the chassis and shaking around the rear end.

Fitment wasn't the best. I had to trim the drivers side of the factory K brace to get the brace to fit.
The holes also barely lined up and the brace had quite a bit of tension in it to get all bolts to thread in.

-- Ryan O. ( NC2 Miata ) January 2025

I have to say this is a Must Buy when doing a suspension upgrade. I had previously upgraded my springs to progressive and the Swaybars as well, but the GWR bracing made the final touch that made the most noticeable difference.
The ride is dampened down, feels solid, planted and predictable. It eliminated any possible ride vibration that was there. Is as smooth as a bran new car. Therefore, goes into the must do category when upgrading suspension components. Trust me, you will feel the difference.

-- Hector R., Goldsboro, NC ( 2010 True Red GT PRHT ) November 2024

I installed the brace kit yesterday. It's well made and seem to tighten the feel off the car especially over rough surfaces. My issues with the kit is that it came with no instructions. It really wasn't that hard to figure out but torque specs would have been helpful. I did call Good-Win and they told me to use the factory specs. The website has some pictures and a explanation of where spacers should go. The main issue on the install is the OEM K-Brace on the left side. I had to use an angle grinder to remove a very small wedge of metal on the K-Brace in order for the brace to fit on top of the brace and lay flat. I don't know if the 2009-13 is different from other years but I couldn't see any other way the get the brace to fit on the left side without that small modification. Maybe Good-Win has a way. There was no issue on the right because the shape of the brace is flat on that side. It also helps to leave all bolts loose in order to get all the holes to lined up.

-- Reed R., Greenwood, SC ( 2009 MX5 ) October 2024