Just wanted to note that I've been emailing with Mike at the factory regarding the torquing of the firewall/engine mount bolts.  I'd read on blogs that these were torqued to 24Nm (17.7 ft-lbs), but this contradicted what was in the Sling 4 Maintenance Manual and what is standard torque for AN5 bolts, which is ~16Nm (11.8 ft-lbs) plus the friction drag.  More specifically, Van's aircraft's torque guide says 8.3 ft-lbs to 11.6 ft-lbs for AN5 bolts.

I've already torqued my lower bolts to 24Nm (though that felt tight to me) and I'm soon going to be torquing the upper bolts, so I wanted to double check.

Mike says that these should be torqued to 16Nm (plus friction drag, which the factory measures as 4Nm, so the factory torques to 20Nm (14.8 ft-lbs)), not 24Nm.  So... I need to remove the lower nuts, toss them and re-torque new nuts to 16Nm plus the friction drag, which I will measure first to confirm.

Anybody think I need to toss the bolts too?  As an experiment in the past I've over-torqued a nut and it didn't take much to destroy the bolt (it snapped into two pieces!).  I don't want to replace the bolts if I don't have to because if I pull the bolts then the engine mount holes will likely mis-align again and will be very difficult to re-line up with the firewall holes.

I'll likely replace the bolts too..

Another note: Make sure you have at least 1 full thread showing beyond the nut.  If you have more than 3 it's highly likely you're tightening against the shank and that is not good.  In that case it's often best to go with a shorter bolt (though adding another washer is possible, though that's a less ideal solution).