Mike’s 1991 Stillen GTZ 300ZX

Filed under: Automotive History,Featured Cars and Projects,z32
by Alvin G @ 3:00 pm on April 17, 2023

We are huge fans of the 1990-1996 Nissan 300ZX and this “Stillen GTZ” example is a unicorn among Z32s. In the early 90’s the GTZ was a limited run, special edition 300ZX Twin Turbo produced by Steve Millen Sportparts Inc. Only 6 GTZs were built in the series, and our client Mike B owns #6 finished in Diamond Black Pearl Metallic. Z Car Garage performed a mechanical refresh with dyno tuning to get it back in fighting form.

From Z to Super Z, by Stillen

Photo by Ryan Brackin

Steve Millen took Nissan’s World Class Sports Car and transformed it into the GTZ. Suspension, engine, transmission and aerodynamic upgrades used in developing this special 300ZX Twin Turbo could be found in Stillen’s performance catalog:

GTZ-specific parts included 17″ Billet Wheels…designed by Steve Millen and Elite wheels allowing 275mm-width tires:

Aerodynamics package highlights included the LeMans-inspired GTZ Rear Wing and GTZ turbo front spoiler that directed air into side-mounted intercoolers. Also shown are the vented front/rear fenders and louvered front panel:

Optional GTZ single tip exhaust system, fitting through GTZ Rear Valance opening. Performance upgrades included Brembo front brake calipers, EVC boost controller, HKS Boost and exhaust gas temp gauges. Catalog scans courtesy of Z32 enthusiast Jay S:

The GTZ received accolades from the press, with an orange example gracing the cover of Road & Track Magazine. Their April 1991 issue featured and extensive review of the car:

“It’s and absolute carnival ride to tip into the throttle, hear those twin turbos spool up and hang on as the GTZ reels in the horizon…a tractable, smooth road car that performs, handles and feels like a race car”

Motorweek put the Stillen GTZ up against a tuned Mazda RX-7 of the same area in their wonderful road test video, you can see it HERE. The GTZ is not to be confiused with the SMZ which was a special edition of the 300ZX that was produced in collaboration with Nissan to celebrate 25 years of the Z car.

Mike’s Z32 Story

Before we get into the mechaincal work let’s hear from Mike and how he acquired his 1991 Stillen GTZ…

“I was working in Phoenix during most of the 90’s in advertising and design for major automotive brands. My job was so stressful but at the beginning and end of each day I had a 30-45 minute drive home. I was driving a 1964 Triumph TR4 at the time and also a 1991 Crown Victoria Police Interceptor. I wanted a 300 ZX TT in black and then I would add all of the body stuff like wings and front valence etc later. Saw the ad for a Stillen GTZ in Autoweek magazine and bought it in 1994 with about 7,000 miles on it. It was like brand new.”

“I bought the car from a lady who had just moved back to Beverly Hills from Hawaii. While in Hawaii she saw the orange GTZ that was on the cover of the April 1991 cover of Road & Track magazine and wanted to have one built for herself. She called a Nissan dealer while she was in Hawaii that was in San Juan Capistrano, CA and ordered a Diamond Black Pearl Twin Turbo. She paid for it with a credit card. It cost about $40,000. It was then trucked to Stillen in Costa Mesa where the car was turned into a GTZ. She spent somewhere around $45,000 on the car to do that. She also had a car phone installed in the center console. It is still there and works. She also had TeleTrac installed which was a GPS tracking device in case the car was stolen, pretty rare at that time. Once the car was finished Stillen put the car in a wooden crate and it was air-freighted to Hawaii. She moved back to the mainland, got pregnant and decided the GTZ was not the car for a pregnant woman so she bought an Infiniti Q45 and had Stillen trick it out. I had the car serviced by Stillen, for the most part, while I was living in Phoenix.”

Mike recalls attending a Stillen Z meet in the 90’s and meeting Steve Millen for the first time with his GTZ. A recent visit to their facility in Orange County in 2022 yielded some great results:

“Steve Millen had sold the company and had moved back to New Zealand, but as I walked up the path to the front door of the shop an older guy was walking out of the building towards me….I was all…that looks like Steve Millen, and it was! We talked for a bit about the car and how he remembered it and the lady who commissioned it. He wrote a short letter for me stating that it was a genuine GTZ, number 6 in a series of 6 built by him. It also stated that my car was most likely the only one still in existence.”

The GTZ at Z Car Garage

We met Mike B in early 2022. He has owned this Z for 28 years and it was not running correctly so it came down to Z Car Garage from SF. We performed a full inspection, resolved some items while it was here and ordered several parts for it:
“I was getting an oil change at a Nissan dealer south of SF a few years ago. While it was on the rack they noticed a few things that needed to be fixed. They didn’t recommend their dealer do the work and gave me Rob’s number and info. It was in the middle of covid so times were weird. They said Z Car Garage was one of the best in the country for Z work and I was happy to hear the shop was about 40 miles away from me. I went down to meet Rob and we discussed what should be done with the car to bring it up to snuff.”

The Z had an older exhaust system on it in rough condition. Rob had one in his parts stash so we hooked Mike up with a fresh Stillen axle-back exhaust system. We replaced all power steering hoses, rack bushings, valve covers, PCV valve, EGR, O2 sensors and everything under the plenum:

We installed Koni Yellow sport shocks F/R, lubed sway bars, and performed a full alignment. The passenger side door window motor failed, NLA but we had one and installed it. The oil was changed and car prepped for smog.

Dyno Tuning

With larger 740cc injectors we made a new chip so we could dyno tune it. It has a Greddy Profec b boost controller, set boost for 91 octane and made 310hp/352tq at the wheels. Solid gains over the baseline of 221hp/236tq:

The Stillen GTZ in action: walk-around, dyno runs and in-car driving with Rob and Mike B, enjoy!

Mike was really happy with the Z Car Garage service:

“Z Car Garage is great! I feel really confident that Rob does the best work out there and really knows his stuff. I took my car in for the boots etc and when all of the work was completed late last year my car was like a whole different beast! Rob did work on the engine like larger injectors and replaced all the fuel lines etc. He did some suspension work as well which took it to a whole new level. My first trip down to the shop, when the car was ready, Rob took me for a spin. That car had never handled like that before or performed like that. I think he said I got about another 100hp to the rear wheels after time on the Dyno. It was unreal to drive.”

“The engine pulls now like it has never before. The power comes on fast and it just feels like it can go and go! When Stillen first built the car they installed Bilstein shocks and Tokico adjustable struts. Over the years I had those replaced and the car never handled as well. When Rob was done with the car it now corners like it used to…like a road grader!! We took a corner near his shop at about 80, and this is a corner I’d usually take at about 40. It handled that corner like a race car, no body roll and tons of grip.”

With the mechanicals sorted, Mike went a step further and had paint and bodywork by our man William. Mike also had the original decals reproduced so the car now looks like it did back when it was built:

Mike’s GTZ at home in San Francisco. Although he’s owned it for nearly 30 years it’s time to let it go to another Z enthusiast. The GTZ is up for auction on Bring a Trailer right now! You can view the auction HERE