I had a debate between these two. I picked the AEM EMS. Since my car is OBD2, the cost of getting a p28 + jumper + Hondata was almost as much as an EMS. On top of that, I still wouldn't be able to change programs without burning EPROM chips and I wouldn't have as much options. On the other hand, if I was OBD1, I would strongly consider the Hondata. Both are very well engineered systems, and I felt the EMS gave me more bang for the buck.