Just put an LGU piston at 195 grams and the shortened transfer port comp. tube in my TX. Uses the LGU seal and 82mm stroke. It has 35mm of preload and makes better than 12 ft. lbs. Funny that I tried it in another TX and it struggled to make 770 fps. I guess the spring in this gun is better, or just more efficient. The shot cycle is snappy, but not harsh and the accuracy has remained stellar.