1.    To improve overall speed, ease of motor installation, and create a more smoother  motor-to-drive train gear mesh, simply omit the 'step down gear' (Motor & Gears - step 6) and lower the motor further into the frame (Motor & Gears - step 7) until the Motor Pinion contacts the Drive Shaft gear.

2.    To further increase speed, for the Axle gears (Motor & Gears - step 1), replace the 2 brass T-Jet idle gears (13/32" dia.)  with 2 smaller (1/4" dia.) T-Jet MOTOR gears. Care must be taken when drilling these smaller gears for the 3/32" brass insert.

3.    The biggest design improvement since the publication of this article is the elimination of the rubber band for pick-up arm tension. The replacement 'spring' is easy to make, install, and adjust.
    From .020" spring steel, form the spring by wrapping around a 3/32" brass tube... then bend the ends to conform to the truck's frame and pick-up arm
(Dia. 1).
    Mount the spring as shown (Dia. 2).

TIPS:
 
Weight:
    As you've probably already figured out, you will need to add weight to the front of your truck to counter-act the force of the pick-up system.
    Weight can be added to the front either in the body/chassis area or to the front wheels.
    Adding weight to the wheels is best (lower center of gravity). However, be sure to add weight EVENLY to each wheel for proper balance.
    The amount of weight needed will vary... depending on how much tension you have on your pick-up arm. Regardless, your truck should be balanced (weighted) so that the truck lifts the front wheels slightly (pops a SMALL wheelie) upon hard acceleration.

Break-in:
    Any freshly built HO Monster Truck needs to be properly broken-in to seat the gears and smooth any sharp edges on the drive train. Do this by simply NOT OILING any drive train components for the first 1/2 hour or so of running time (oil motor as needed).
    At first, run the truck 'freewheeling' (hold above track) only about 30 to 60 seconds at a time... checking the motor for signs of overheating often.
    As the truck starts to 'smooth' out, take a few laps... again, keeping an eye on the motor.
    Once things seem to be as smooth as they are going to get... OIL EVERYTHING that moves (except shoe deck/pick-up arm area).
    The one thing you'll learn about Monsters... they LOVE oil !!!