2017 Fiesta ST OEM+ Build: Modification Log w/Data

Background: I just acquired a 2017 Fiesta ST with ~25,000 miles. The car is an entirely unmodified, one-owner California car that's been well maintained, so a good starting point from which to build. I am planning to do a number of things to the car, going for a mild 'OEM+' type of build. My goal is to build the ultimate back road/street car. While I am open to getting the car on track, I want to build it for the street. Usable power, maintaining the wonderful driving dynamics these cars come with from the factory. No interest in just spinning tires or winning highway roll races.

Planned modifications (most of which I already have):

1. New wheels (I just received a set of 17" OZ Superturismo GTs from Tire Rack wrapped in G-MAX AS07s for now, summer tires when it gets warmer)
2. Lowering springs (Swift) are in the mail
3. Accessport in the mail (coming preloaded with the Mountune 93 octane file, but planning to try dizzy, stock cobb, stratified and others)
4. Minor tune/motor ancillaries
   1. Symposer delete
   2. Drop in filter (ITG)
   3. Colder plugs (NGK Ruthenium)
   4. RMM (vibra technis)
   5. Intercooler (have not yet procured, as it's still very cold out in the north east)
   6. ST200 airbox w/cold air feed hose (have not yet procured)
5. Possibly a mild exhaust at some point (FSwerks)
6. Open to other ideas! But I'm trying to keep things moderate.

The plan: measure the performance of the car with every change I make, just to help quantify the gains associated with any given modification. This evening, I started very small with the drop in ITG filter. I didn't expect any appreciable gains, but the plan is to measure every single step of the process, so I did.

The methodology: I decided that a third gear pull, measuring 30-70 mph and a number of sub-segments within that range (30-50, 50-70, 40-60), would work best. This range doesn't require any gearshifts and won't induce much/any wheelspin. I'm doing these tests on the same stretch of road, and will run them with the same fill of gas (half tank, shell 93). I recognize that as ambient temperatures get warmer, it will muddy the data a bit. But my test equipment (Racebox Mini) calculates density altitude, which can be used to normalize data. For each modification 'phase', I am doing 5 runs and counting the best time achieved.

Initial results (all runs are in third gear, sport mode):

Baseline (Stock Car):
Slope: 0.4%
Max acceleration (G): 0.22
30-50 MPH: 2.86
50-70 MPH: 3.07
40-60 MPH: 2.91
30-70 MPH: 5.94

Phase 1 (Stock Car + ITG Panel Filter):
Slope: 0.5%
Max acceleration (G): 0.23
30-50 MPH: 2.76
50-70 MPH: 3.02
40-60 MPH: 2.83
30-70 MPH: 5.79

Phase 2 (Phase 1 + 17x7 OZ Superturismo GT Wheels and General G-MAX AS-07 Tires - 2.0 lbs weight savings per corner):
Slope: 0.2%
Max acceleration (G): 0.27
30-50 MPH: 2.70
50-70 MPH: 3.05
40-60 MPH: 2.79
30-70 MPH: 5.75

Backup data/outputs (this testing suite has a bunch of cool features, and can output all GPS/accelerometer data at 25 hz, meaning measurements every 1/25th of a second):
Baseline (Stock Car):


Phase 1 (Stock Car + ITG Panel Filter):


Phase 2 (Phase 1 + 17x7 OZ Superturismo GT Wheels):

ST200 airbox supposedly doesn’t flow much better than OEM, so potentially unnecessary.
does the car have an upgraded rad?
consider tuning with TunePlus

+1 on the radiator. Replacing the exhaust may improve the sound but won't improve performance

also, what is OEM+? I have heard several different opinions on it

Sounds good on tune plus and radiator. Any reason tune plus is preferable to the other tubes listed?

OEM+ is a car that is enhanced but does not sound or appear heavily modified. It makes uses of upgraded components that look/sound factory (eg ST200 airbox).

NOT if you want to (or for some reason must) use Shell V-Power 91/93 fuel.

I've been told that Adam flat out refuses to tune even a factory turbo, simple bolt-on FiST if the owner is using (or insists on continued use of) that particular gasoline.

Interesting. What fuel does he prefer? A lot of Porsche owners who have tuned their current gen 3 liter 992 motors have had much better luck with shell than other brands of gas. It’s all I’ve used in my NA 4 liter with great results.

Update: just added test results with slightly lighter OZ Superturismo GT 17x7 wheels on the car (wrapped in General G-MAX AS-07 tires). These weighted in at 40.5 lbs per corner. The stock wheels w/tires weighed in at 42.5 lbs per corner, so some modest unsprung weight savings with the new wheels/tires. Gains were modest, as expected.

One other test I would like to perform is one that measures wheel hop with and without the vibra technis RMM. I may also experiment with a torsion bar. I am going to try to figure out how to mount a gopro underneath the car to capture the front wheels/wheel hop under hard acceleration in 1st/2nd.

I believe Chevron and/or 76 (maybe? I forgot now), neither of which can be readily found along our east coast location (or at least none in my area currently).

It's bad enough I must drive well over an hour away to get E85 if I ever tuned for that, to have to make a road trip just to be able to use his 93 tune is totally out of the question for me.

For what it is worth; none of the other tuners I ever contacted to ask about this supposed 'additive problem' in the V-Power that Adam claims prevents him from tuning properly have ever experienced the same problems, let alone refused to tune on a certain brand fuel.

In fact, they were all bewildered and incredulous that he had a problem with any top tier, premium fuel out there, so .