Most people think you have to return all the fuel not used, but that is not true. You can have a a short dead head system off the regulator if you do it right.

I like the ones that look like a carb but have the ability to control timing and maybe even N2O and or boost....Keep it flexible, and it never gets old, and if needed, you can adapt to different race classes.

Also, if you have the ability to change the opening of the TB form 1:1 to progressive is really helpful on big engines....When you get it right, it can be way too snappy...S,aller motors might like it...