The Stage 1 Calibration
With baseline data in hand, Mitch built the Stage 1 map. As he described it: “We basically just did the Stage 1 tune but took a little more knock out.” He also richened the air-fuel ratio under load; running a slightly richer lambda keeps the engine happy and safe on marginal fuel.
The changes made:
- GT4 throttle and torque request maps applied
- Ignition timing optimized (with additional knock buffer for AZ fuel)
- Fueling enriched under load (richer lambda target)
- Rev limiter raised to 8,000 RPM
- Cold start elimination applied
- PSE true ON/OFF programmed
- Auto Start/Stop permanently disabled
The Result
Stage 1 result: 386 whp (Run 7)
That’s a gain of approximately 45 wheel horsepower over the stock baseline on this specific car. For context, that delta includes the benefit of already having the Soul OAPs installed. A standard bone-stock GTS 4.0 baseline would start lower, so the peak additive gain from the tune would appear larger relative to true stock.
The area under the power curve above 5,000 RPM tells the real story. That’s where the throttle tapering was stealing power — and where the Stage 1 calibration hands it back.
What’s Next for the Platform?
The GTS 4.0 Stage 1 tune is the foundation, not the ceiling. Mitch mentioned several directions for additional power on the 9A2 4.0-liter platform:
93 Octane: For readers who can source quality 93 octane, the gains over ACN91 are meaningful. We may blend 100 octane pump fuel with 91 to make our own 93 blend which we’d prefer over an octane additive.
200-Cell Headers: Mitch’s assessment is that after uncorking the OAPs and dialing in the software, the next meaningful mechanical restriction is in the headers. A set of 200-cell catalytic headers would reduce backpressure and give the tune more to work with.
The GTS vs. GT4 Question — Does the Tune Close the Gap?
Here’s the question every GTS 4.0 owner wants answered: after tuning, is there actually a meaningful power difference between a tuned GTS 4.0 and a tuned GT4 with identical exhaust mods?
Given that the engines are mechanically identical and the power separation is software-only, it seems obvious. With the tune our car now makes almost as much at the wheels as the previous engine power.
Final Thoughts
The M-Engineering M-Tuner Stage 1 calibration is the single highest-value-per-dollar modification available for the Cayman GTS 4.0. There are no parts to install, no exhaust to cut, no hardware to source. You’re paying to remove a software restriction that Porsche imposed to protect a market segment.
For owners in the Southwest US in particular, the combination of throttle map correction, timing optimization for ACN91, and the cold start and ASE eliminations makes this feel like a different car. The engine finally does what your right foot asks. While far from a straight line screamer, the car legitimately pulls hard to redline unlike before.
The dyno session video from CPR is embedded below. Next up in the project: are some protection parts from Rennline.
Stay tuned.
3 comments
Man, the car is making good power. I figure Project Cayman T is around 320whp on 91 octane with all the stuff I’ve done to it. That’s probably around what your car would put down stock, before the OAPs. So you’re up around 65-70whp on me, give or take. With some planned mods somewhere in the future, I think I can gain 20-30whp while staying on 91 oct and stock cat, but I’m not going to get close to where you already are.
Definitely have to get you to drive it to see what your thoughts are. As you’ve said it’s a heck of an engine. I bet your car’s torque curve is pretty sweet at low RPM’s especially. Lot’s of different flavors of ice cream in the Porsche lineup.
Oh yeah, thank goodness you can eliminate the pops and bangs.