Tuning Fx impact M3 .35 and .30

Not sure if you have the transfer port with two settings, one for P and the other S, do you have one of those? If so it may be just as simple as turning from P to S 180 degree turn of the barrel. If not that, only other thing i could think of is starting from scratch with the factory tune settings. Also, the .35 has different internals than the other FX M3's. 
 
840fps @81 grain 135bar.

I emailed fx and asked about this, and got :

This might be your C1 being too far out. If you remove the valve housing and knob from the rifle (AFTER DEGASSING THE ENTIRE SYSTEM) and measure with a depth gauge on a pair of calipers or a ruler. You want your C1 to stick out by 5.3 to 6.5 mm while it is FULLY seated in the rifle. The smaller this number is the higher the potential power of the system, but there is a point of diminishing returns. If the C1 is more than 6.5mm out, then dramatic power losses will be seen. 

Will try to place this at 5.5mm with the .35 power kit and test again , fingers crossed
 
840fps @81 grain 135bar.

I emailed fx and asked about this, and got :

This might be your C1 being too far out. If you remove the valve housing and knob from the rifle (AFTER DEGASSING THE ENTIRE SYSTEM) and measure with a depth gauge on a pair of calipers or a ruler. You want your C1 to stick out by 5.3 to 6.5 mm while it is FULLY seated in the rifle. The smaller this number is the higher the potential power of the system, but there is a point of diminishing returns. If the C1 is more than 6.5mm out, then dramatic power losses will be seen. 

Will try to place this at 5.5mm with the .35 power kit and test again , fingers crossed

I don't think your too far off; with the second reg at 140bar I'm at @ 865-870fps. Keep us posted on what you find.
 
You may want to try opening the valve adjuster all the way and see if that makes a difference. If you have a 4 groove valve adjuster housing, the maximum valve opening is 1.5 turns open beyond the 4th groove. With higher power tunes, setting the valve at the 4th groove can be a restriction.

If you have a 6 groove valve housing, full open setting is at the 6th groove. Not sure why all the M3s don't ship with a 6 groove valve housing...