I have the original Spark, Originally I put it in my P0 L, But I didnt think far enough ahead, I have since moved it to my P11, again this is easy to use, But I always reccomend this location (as well as all other locations) to be installed by a pro.
Really the choice of location is your, but dont be like me.
Plan ahead.
I did this afterwards, and made a hand map, including the implants and locations I wanted, I crossed them off as I got them.
This worked well for me