SPEED Airsoft took note of this and designed a new adjustable trigger specifically for HPA applications. The new trigger features two adjustment set screws which allows the user to adjust both the stroke distance as well as the over-travel. They also designed it so it can be adjusted externally so you no longer needed to take apart the gearbox in order to make adjustments.
Airsoft Junkiez kindly sent us a sample of one of the new triggers to check out and we have been quite pleased with the overall design of the trigger. It was a breeze to install and adjust and the fit and finish of the trigger is top notch. We did find that the spring which comes with the trigger was a little light for our taste so we did end up swapping it out for a slightly stiffer spring to get a little more feedback from the trigger. One thing to note is that these triggers are not designed with the sole purpose of giving a rifle a “hair trigger” but more to make the trigger as precise as possible. Since the over-travel can be adjusted, you can set the “hard stop” to be right at the point the system fires so the trigger movement will stop at the time the shot breaks. This can aid in accuracy during rapid follow up shots and allows you to precisely find the firing point in the trigger’s travel which is a great help when you need to time a shot perfectly. 
For those of you who have compared shooting a Fusion Engine to a JACK, F1 or other systems on the market, you would have noted that the trigger on the Fusion Engine felt noticeably more “precise”. This is because we are able to set the hard stop to exactly where the trigger engages the micro switch so there is no over-travel with the factory trigger. We were able to do this since everything is contained within the CNC machined solid side plate of the Fusion Engine which gives us complete control over tolerances. We were not able to do this when designing the switchboard used by the F1 and JACK since we had to account for the varying tolerances of gearboxes made by different manufacturers. Since the stroke distance of the trigger will be different from brand to brand, we had to build the board with a micro switch that allowed for a certain amount of over-travel beyond the firing point to prevent the micro switch from being damaged. Although this trigger does not quite reproduce the same clean “break” that the Fusion Engine trigger has, it does significantly improve the feel of the trigger and comes very close to the feel of the Fusion Engine’s trigger in terms of precision.
One important thing to note for anyone installing one of these triggers is that, since the trigger is adjustable for over-travel, it can still over-travel and damage the micro switch if it is not adjusted properly. Specifically when installing a JACK or F1 since gearboxes from different manufacturers can have slightly different dimensions so the shell may not always stop the trigger before it bottoms out on the micro switch. Therefore you must always adjust the over-travel screw and tune it to your specific gearbox. The best way to do this is to tighten the screw to the point that the trigger will not contact the switch when pulled. Then, with the rifle pointed in a safe direction, back the screw out while depressing the trigger until the system fires. You could back the screw out a half to a full turn beyond this to provide a little bit of a cushion past the trigger break just so long as the trigger hits the hard stop before it bottoms out the micro switch.
Overall we feel that the HPA Speed Trigger is a great upgrade and we highly recommend it for anyone looking to improve the responsiveness and feel of the trigger in their PolarStar system.