Doesnt hurt to use a larger line like an 1 1/4" or 1" instead of a 3/4 all the way, also make sure there is a union at the coil so that the point where the water leaves the coil can be cleaned.
I always thought the trap is where it usually needed cleaning. I was just going to usa a T fitting leaving the coil with a cap so I could have access later for cleaning the trap. Maybe I need to re-think this and make the whole connection including the trap so I can take if off for cleaning.
Why would going to a larger drain line help anything? There's not that much volumn flowing.