A few...
* sand the edges of the battery slots at a 45 degree angle on both sides to let the batteries sit as low as possible without touching the floor before the chassis. Be careful not to allow them to sit too low especially if running on asphalt. Your batteries may receive an unwanted shaving.
* lightly sand all the rest of the edges of all the graphite parts and apply CA glue to seal them. Let the glue completely dry before continuing or you may need to receive an unwanted shaving.
* Don't tighten the bulkhead screws too tight or you may strip them when trying to get them off.
* Use a small dab of thread lock on the wheel screws, especially if your running mod. I've lost a few wheels/screws by not doing this.
* Shave the shock mount on the rear arms down 3mm if you plan on using the outer hole. Most rims tend to eat into the shock ball end if you don't. Make sure you keep the surface the same angle as it was otherwise the ball screw may not seat right when tightening the shock down.
* My tips on shock building are at
http://www.teamxray.com/xforum/viewtopic.php?t=602
* You may need to polish the arm pivot pins and/or shave the inside of the arm pin slots (not sure if thats the correct term, but you know what I mean) to make sure the arms rotate freely. Test the rotation after you've added your rear toe-in & front in-board toe-out (
http://www.teamxray.com/xforum/viewtopic.php?t=618 ), and tightened the plastic pin holders to the bulkheads. With the toe angles, you may need to shave a little of an arm, holder, or wheelbase spacer to let the arms rotate freely on the pin.
* When installing the servo, I put the aluminum mounts on first and lightly snug the screws, then I screw the mounts tight into the chassis (not too tight as to avoid stripping them upon removal), and finally tighten the screws holding the servo to the aluminum mounts.
* If you shaved the battery slots, you'll probably have to add some cushion under the battery holders to stop them from bouncing up and down, but be careful not to add too much so you have to push hard on the screw to tighten the holders down. The FK chassis is not too stiff and you can add tweak if you put too much pressure on the battery holders.
Can't think of anymore right now...