I'd stay away from the JP-1 pipe with the Mach engine. Waaaay too much torque/wheelspin. Jp-2/3/4 will be much better.
I'd also suggest lining the bottom of the battery box with a piece of lexan. Some people have had that screw in the bottom screw up their RX packs.
If you really want to bullet proof the car: do the outer steering tie rod modification and capture the ends with another set of 6.6 mm balls, 5-40X1/2" screws, 5-40 washer. If you do this I'd suggest an aluminum front inner hinge pin cover-inplace of the plastic. When I did this mod the plastic inner cover started breaking more frequently. The force has to go somewhere I guess. LOL.
I also recommend an aluminum steering servo arm.
As for the A-arms, it's nice to have spares but I bet you never take them out of the package. Never heard of anyone breaking an arm on the 8 or 8T.
For convenience sake: try a quick change engine mount. It makes clutch maintinance a breeze. But if you do this the roto-start back plate will need to be dremeled significantly. I had to dremel mine till the bottom screw threads were showing. I used it this way for about 5 gallons till I got a starter box.