2018 Mustang GT Update: Catalytic converter replaced at 8300 mi

Got a CEL at ~8300 miles on the car. Pulled code P0430 catalytic converter efficiency on cylinder bank 2. Took it into a Ford dealer, waiting to hear back tomorrow. Guy at AutoZone said it’s probably spark plugs (which were replaced when I got the Roush SC installed) but I think it’s the O2 sensor. We shall see hopefully tomorrow morning.

UPDATE: Got a call back from the dealer, it seems the cat has actually failed. Shocking for a car with just around 8300 miles.


2018 Mustang GT 1st Year Ownership Report

Haven’t posted in a while but I figured I should share this first milestone of ownership. I am thinking about doing a Car & Driver style guide of recording events in my car’s history here. Here is a breakdown of what has happened so far in one year of owning this car:

Mileage: 7015 mi

Average MPG: 14.1 mpg on 93 octane fuel (mainly city driving)

Services and Modifications

  • 1 Full Synthetic oil change
  • ROUSH Phase 1 Supercharger installed
  • ROUSH Cat-back exhaust installed

Major issues: None

Minor issues: Typical Mustang interior rattles and absolutely awful P Zero Nero A/S tires

Total maintenance costs: $120 (oil change)



The 2020 Mustang Shelby GT500 finally unveiled + I got a new exhaust!

Sorry for the radio silence as of lately, I have been quite busy with college and work. I am very late to the GT500 news round but here it is, the mighty GT 500!


The full press kit is available here: https://www.mustang6g.com/forums/threads/official-2020-shelby-gt500-mustang-press-release-specifications-photos-videos.115819/ but here is a quick run down:

  • Supercharged, cross-plane crank 5.2L V8, output of 700+ HP projected (numbers not finalized). Utilizes a 2.65L TVS roots-type supercharger by Eaton (same rotating assembly used by the 2018-2019 ROUSH Phase 1 SC Kit and the Corvette ZR-1!)
  • 7-speed Dual Clutch Transmission sourced from Tremec (same guys who build the GT 350’s 6 speed manual), with shift times of under 100ms
  • Available Carbon Track Pack with 20″ carbon fiber wheels and GT4 class carbon fiber spoiler
  • Massive 16.5″ two piece steel brake rotors matched with 6 piston Brembo calipers
  • Michelin Pilot Sport 4S or Cup 2 rubber
  • All new hood vents and cooling system up front
  • Interior upgrades with new materials and finishes

Looks like an absolute monster to me, can’t wait to see more info and what they look like in person. The DCT is what should give it a real edge over the ZL1 and the Hellcat, but we just have to wait and see.

I also got a ROUSH Cat-back installed on my 2018 GT and what a difference it makes! The sound is raspy, aggressive, and just plain loud. Really makes a huge difference in the driving experience and adds even more fun to an already fun daily driver. I will be posting a sound clip soon.

I will also try to start posting more often here and on The Stack Underflow Blog. Till next time.


Mustang Shelby GT500 Leaked + first time driving the ‘18 GT in cold weather

At a dealer event just this past week the 2020 Shelby GT500 was unveiled and unsurprisingly someone leaked a pic of the car: https://www.mustang6g.com/forums/threads/leaked-gt500-pics-and-specs-from-dealer-meeting-today.111539/

I honestly think it looks pretty good, but there are some mixed opinions online. I think they played it safe sticking to the 15-17 headlights instead of the 18 update. Not that big of a fan of the black painted bar in the middle of the bumper, looks too much like the 2019 Camaro SS front end and should be painted body color instead. Very excited to see the rest of the car though. As for performance numbers it’s still unknown, I’m guessing around 740-760 HP at the crank. Considering they’ll almost certainly be using the 2.65L TVS blower from Eaton which is also used in ROUSH’s Phase 1 SC kit for the ’18 GT, making over 700 HP should be pretty easy. Transmission options are still unknown with reports of a new Tremec Dual Clutch being the only option as well as a 6 speed Tremec manual being standard and the 10R80 being the auto option. I am curious how the 10R80 would fare in such a high horse power variant of the Mustang as well as how much they were able to dial in the shift mapping. Seeing a dual clutch would be exciting too, we just have to wait and see.

Apart from that I have some anecdotal things about my Mustang I wanted to share. We recently had a cold front in North Texas meaning this was the first time I had my Mustang during 40 degree weather. I noticed somethings that I wouldn’t have before regarding fluids and how long they take to warm up. I’m running 5W50 full synthetic as per ROUSH’s requirement and it takes quite a while to reach operating temperature. A solid 20 minutes of city driving brings the oil temperature needle just a quarter into the green zone (in the gauge mode section of the center display). Because of this I’m unable to rev the motor out for a while which is annoying because I am used to hitting WOT on my morning commute during the summer. The transmission fluid also takes a while to warm up too and shifts feel a lot harder even in regular driving mode before you hit around 125-150 degrees Fahrenheit. Once warmed up though my blower loves making boost since the ambient temperature is so low. As long as roads are dry I am able to really rip the car a lot harder than I did over summer since it was in the 100s most of the time. Should be interesting to see what happens if it snows because the all season P Zero Nero’s are not that great even in the rain.

10R80 Transmission ‘Adaptive Learn’ with ROUSH Stage 1 Tune

If you have a 2018 Mustang GT equipped with the 10R80 automatic transmission and have installed a ROUSH Performance Stage 1 supercharger you would have noticed harsh downshifting from 3rd-2nd-1st in Sport/Sport+. I noticed this immediately after the install and after consulting Mustang forums this is definitely a known issue.  Reviews for the part on Roush’s website suggest that the issue is currently being worked on. In the meantime, drivers are confined to the regular “Drive”. The car still pulls hard but doesn’t rev out as much compared to Sport/Sport+ so it’s just not as fun. Determined to keep driving in Sport+ I figured out a way to get smoother shifts from 3rd-2nd-1st. The issue only occurs during light braking and coasting as the car will hang in 2nd before slamming into 1st if coming to slow stop. One solution is to always slam on the brakes (bad) or to use light braking modulated with a firm brake to bring to car to a halt. For example when in traffic you’ll ride the brake pedal as you slowly come to a stop. Instead of easing into the brake while you are preparing to stop apply firm pressure at the very end and the transmission will slot into 1st smoothly. This takes a while to get used to but once you get it you’ll be able to stop very smoothly. Interestingly enough I believe that doing this enough, along with the 10R80’s ‘Adaptive Learn’ feature, seems to have smoothed out the harsh shifting. ‘Adaptive Learn’ is a feature built into multiple Ford transmissions that progressively learns shift patterns and adjusts them over time. It is known that reflashing the PCM resets the learned data causing harsh shifting and I believe that with the Stage 1 ROUSH tune that the shifting data had been reset. I have driven about 800 miles since the tune had been installed and recently I noticed that down shifts have been a lot smoother in lower gears. The jolt from 2nd-1st if coming to a very slow stop and coast is still there but occurs less frequently. I have reason to believe that the adaptive relearn feature has corrected a majority of the issue for me. It is still possible to get smoother, stock tune like shifts with an updated tune from ROUSH but an interim solution, at lease for me, is to continue to drive it in Sport/Sport+ and try to get the lower gear shifts smoother when coming to a stop. Over time the downshifting will get progressively smoother allowing you to enjoy the high revving, late upshifting nature of Sport and Sport+.