Hah cool, I still wouldn’t run a 6.01 on anything other than a pistol.
6.03 or 6.05 for an AEG.
With 6.01 straightness is very important and it doesn’t take much dirt or crap BBs for things to go wrong when your barrel is longer than a pistol AND your pumping 25 BBs down there EVERY SECOND!
Personally if I were you I would;
Buy a new M100 and M90 from a known brand.
Step down to 7.4V or get a slower motor - I can’t believe the motor you have is 18K, it doesn’t add up, you must have a good one!?
Another option for you is;
SS what you have by 3 teeth, that should drop you about 45 FPS.
Put your sorbo pad in, that’ll drop another 5 FPS.
SS BY 2 TEETH FIRST AND TEST - YOU CAN TAKE ANOTHER TOOTH OFF, BUT YOU CANNOT PUT IT BACK ON!
Stil a good practice to buy a couple of known springs for your reference.