Here is a bunch of documentation in zip format from the old Huntley
A couple of htm documents and a word document.

http://www.needmoreboost.com/testarossa_td/arcII.zip

 

Most likely a function of chips and not the ARC-2. I've noticed it works well when the chips are close to what you want and you need some minor fine tuning. My APE based chips were always rich in the midrange and out of the tweaking zone of the ARC-2.

For you old farts, the ACCEL **** is like an accelerator pump on a carb. When you apply throttle, it will give an extra little spurt. Once you have all the ***** pretty close to where you want them, adjust the ACCEL to the point where you get the cleanest REVs off idle.