I wired my own engine harness as well, I don’t know if there are any plug and play harnesses for our cars. I think Holley would be the closest thing, but they come with their own harness and you integrate the ecu.
What capabilities are you looking for that the stock coyote ecu can’t do?
The biggest thing is progressive nitrous, but I'm also wanting scramble and EGTs. Idk maybe I'm underestimating the coyote ECU, I also want to be able to make it ignore the MAF when it pegs because I'm likely gonna make enough power to peg it once I switch to the twincharged 4v setup. But the biggest thing is no needing something like HPTUNERS to mess with the tune. Me and my dad adjust shit all the time at the track because he's excellent at judging what needs to change with the weather (former pro stock crew chief for 2 teams and current racing chassis builder, he knows nothing about electronic engine management, he's all carburetor and distributor)
I'll throw my ecu capability wishlist in here:
‐MUSTS
MAP+MAF both
Dual widebands
6r80 or early 4r70W control (preferably 6R80)
2 stage v8 fuel injection
Nitrous control
Boost control
Datalogging for most data channels
Odometer in dash (may be seperate from ECU)
‐NICEs
ABS
Traction control
CAN capability
Power distribution or comms with PDU (preferably through CAN) (if I use a PDU)
Speed compensated volume? (Crazy wish ik)