I can tell you they run fine. Stock efi is fine. I did my own harness, and do not have street & performance do the flash. Two years ago they did nothing "in house," Call Dave at B&G Chrysler in Michigan, he does a decent job. I recently got 24 mpg with a 6.1 cam in a 5.7 hemi, with a tko600. Drivability and reliability is awesome. Have been on three 700 mile round trips, and no troubles. I would be glad to help anyone that needs it. As far as the programmable stuff, I do not think it is needed until maybe up to 500 hp. A bought harness is around 950$ from HotWire and 450$ or so for the computer and a flash (I think). Its awesome inmy opinion, it would only be better with a stroked efi 6.1.

Good luck

Justin