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I recently acquired a new to me GS and obviously you have to toss it on the dyno to see what you are working with...right?
2019 GS M7 manual
9,544 mi at the time of the dyno
Only mods are AWE midpipe and MGW shifter and Attack Blue air filter
88* day (feels like 96*) with 63% humidity
First graph is exhaust valves open vs closed. That is ~20hp/~10tq less leaving the valves closed. Both runs started around the same engine coolant temps
393/383 open
372/372 closed
Second graph is compared to my previous C5Z on this same dyno with full exhaust/BTR stage 2 cam/ported LS2 TB/ported Dorman LS2 intake/LS7 air bridge/LS7 card MAF on speed density/E85
Just shows the peak numbers do not tell the full story. The C5 was built to pull more RPM and around autocross/midrange power. But the HP/TQ at the low end of the LT1 6.2 is what gets you going!
No major plans for the car other than maybe Longtubes and E85 kit "just because" it's so easy to bolt on and cheap ($300 DSX kit). I probably won't even mess with a catback since the stock one works and sounds good enough that spending the $2000 for a valved setup isn't worth the performance.
Just thought I'd share my findings.
Last edited by smitty2919; Jul 2, 2025 at 08:39 AM.
Any idea how much increase on this car would be with Kooks 1 7/8 long tubes followed by a professional engine calibration/tune ?
I am considering a C7 Grand Sport possibly and would only do the above mods.
C7 GS dyno results
