First thing I have to wonder is how he's beating you with a Titan motor in a Stampede. The Titan 550 motor is a 14 volt motor and would be really seriously slow on 6-7 cells in a 'pede, unless he's running 12-14 cells. ?????? You sure he's not running the stock 20t Stinger motor?

Anyway. It's hard to say exactly but from your discription. First leave the rear toe in at about 1.5 degrees. But toe out the front to about 1 degree. Toe in on the front with 4wd will take away a lot of on power steering into the corners. The stock springs are way far too soft for high traction like carpet. You'll get a huge amount of body roll. Go with harder springs. Something like Losi Orange or Green all around. If you don't have much jumping to do then go with 100 front and 80 rear on the shock oil.

Making a set of swaybars is a good option. All you need is a piece of 1/8" piano wire, some fuel tubing, some 1/8" collars. 4 long rod ends with balls in them and long 4-40 screws. Drill a hole in the top suspension arm out where the arm forms a "T" right in the center of the arm. Run a 4-40 screw up through the arm into the long rod end. Do both sides. Then slide a piece of fuel tubing onto a length of the piano wire. About 1½" and put a collar on each side of the tubing. Remove the front bumper and slip the wire with tubing into the space in the bumper mounts between the screw holes. (you'll get the idea with the bumper off.) Adjust the wire so that when bent back at an angle the end's of the wire will pass through the balls of the rod ends. Bend the wire as needed and replace the bumper over the "swaybar". It's a cheap setup but it works. Do the same for the rear if you need it.

Mount your battery packs on the underside of the chassis rather than on the top side. Buy an HPI body mount set. Use the long body posts. Drill through the battery mount holes in the chassis all the way through. Run a long 4-40 screw through the hole and into one of the long body mounts on the underside of the chassis. Do both ends then put in a battery pack and slide the strap down on the post's. Pin the strap in place then cut off the excess post. Tape or zip tie the battery to the battery strap to prevent the pack from sliding sideways.

I assume you used the stock foam inserts that came with the BowTies? If so they are way too soft for high sidebite. If you can get away with it, bake off the tires from the wheels and get a good set of the ProLine 2 stage foams. It will stiffen up the sidewalls a lot. Then use a pair of sharp clippers or sissors to clip off the very outside row of lugs on the inside and outside of all the tires. Clipping the single outside row of lugs will help the truck track straighter and be less "twitchy".

Run the suspension with the Front lower arms level and the rear lower arms just a bit sagged.

The truck should now be very fast into the corners and be well planted alround.