Back on topic, the car now has a HPI D-Box compliments of my sponsor and it looks to be a better option than the cheap gyros that appear to do the job okay, until you try one of these!
The HPI D-Box aka drift assist aka stability system is very small and compact. It mounts on it's bottom or top edge, depending on your cars servo mount orientation (clockwise left or clockwise right mounting) and your resulting transmitter settings (steering reversed or not). I've heard some say gyros are better mounted on the tail of your car as there's more sideways acceleration there (bigger arc) but I find I prefer it about 2/3rds rear between the axle lines, but the choice is yours. Keeping it in the top deck isn't necessary but it's easier to adjust there.
There is just one adjustment as the normal 'setup' screw pot is replaced by a startup software routine in the tiny box, making this one a simple plug and play installation. You still have a small adjustable gain 'pot' that allows you to tune the degree of 'assist' the system gives, from 10 to 100%. The assist is essentially where the box steers the car into a slide by providing opposite lock, so catching the back end before you've lost it. The amount of opposite lock is determined by the rate of acceleration of the drift turning motion and the % gain selected. As you reduce the gain, so the more absolute control is returned to the driver but the less help is given. When you are learning the ropes, try 100%! The assist, by the way, operates for 100% of the time the car is turned on so it will even help the car to drive straight on those longer straight sections that take you to the start line, so fewer embarrassing slow spins!
So, is the HPI worth the extra? The budget gyro I started of with was cheaper but the first example delivered didn't work at all. The replacement did work but needed to be setup, and not just the once! The controller steering sub-trim was a place I got to know very well! Many of the budget units also seem to be easily over excited! It's not something you seem able to tune out with their gain controls either, as they seem to be constantly correcting the steering angle whilst driving in a rather jerky way. It worked but looked very untidy on the track and the noise from your servo can be a little worrying too.
By contrast the D-Box is silent, responsive and smooth. On start up it's led blinks to tell you it's completing the setup stage which takes a second or two, after which the led goes constant and the steering may be operated. As you swivel the chassis in your hand the opposite lock is applied smoothly and solidly with no 'flickering' of the servo.
I've not yet been able to find any information regarding the programming algorithms to describe how the box actually applies steering adjustments to incorporate both the gyro's input together with the driver's input. For example, as you initiate a drift the box starts to add countersteer but you too will be doing so via the steering yet the box somehow combines both inputs rather than ignoring one of them or simply adding both additionally - yet you are very much still in control and can steer the car through varying radius curves and transitions just as you would with a much easier to drive 4WD chassis.
So, having tried both budget and quality drift gyros, what would I recommend? I've been completely won over by the HPI D-Box. It's been around since the mid/late noughties and shunned by the drift fraternity, and correctly so as it had no place in a 4WD chassis, but we're now attempting to achieve what has, since the dawn of RC drifting, been the 'Impossible Dream' of 2WD drifting, and the gyro has now found a place. So it's been well tried and tested and shows none of the issues found in some budget units. It's simple to install, simple to adjust and makes 2WD drifting...well, not simple but with practice, very possible!
If you are just dabbling with the idea of trying 2WD drifting on the cheap then a cheap gyro for around £20 may seem a good idea. However, 2WD drifting is addictive so, take my advice, save yourself that £20 and go for the real thing from the outset and see the rewards on the track!
Next, back to rear wheel tyre testing. We know that on new, clean Prima GT carpet both the T-Drift and TN 219 control tyres work well enough but which is best? Ballast and balance too needs more testing, and you'd expect that to affect tyre choice too. It is, of course, a bit of a black art!