I'm debating between a plug & play Emtron for Evo8 and a KV8 + adapter harness. The P&P would certainly be more compact and simpler (and cheaper), but I'm not sure what inputs/outputs I'd be giving up and am also considering that I could move a KV8 box to another car in the future if I wanted to change up the Evo ECU again later. Anyone have any thoughts on this choice?

I am currently putting in a Ohm Racing engine harness built for running an Emtron KV8 in my Evo 8 because the factory engine harness was butchered and brittle.

I would do the KV8 with Boomslang adapter harness to get maximum use out of the standard KV8 I/O and to future proof its use in other potential cars.

I want to be able to revert to stock ECU, so I wouldn’t be replacing the engine harness. Do you know of any company other than Boomslang making an adapter harness to re-use the original engine harness? Just trying to figure out options.

Totally understand what you need. In the US I can't think of any other company that does production level adapter harness's better than Boomslang.

What about outside the US?

Lambspeed Racing in Australia has one other than that I think its all custom by a shop that does motorsport wiring. \
https://lamspeedracing.com/collectio...hi-evo-7-8-gsr

The Plug and play KV8 does not come with on-board lambda so you’d have to buy the controller for that. IIRC the price difference between plug and play or going with universal and boomslang was ~$300 when I was looking into it.

I asked Emtron the same question recently. They were super helpful and quick with the responses.

The main differences between the plug-in and the KV8 are essentially.
-The KV8 has dual onboard lambda controllers, the plug-in doesn't have onboard lambda and will require an ELC1 (CAN to Lambda).
-The KV8 supports dual electronic throttles, the plug-in doesn't support electronic throttle)
-The KV8 supports saturation and peak and hold injection but the plugin only supports saturation styles injectors.

The other major difference is the I/O count. The plugin has an expansion port which is great for flex fuel and some additional sensors whereas the KV has a 4-connector system with a huge I/O count. The plug-in uses the same software as the KV which allows for all motorsports functions to be used but you are limited by what sensors you can fit in the unit. We also have an expansion device (EIC16M) which allows for additional sensors to be used but realistically you are better off using a KV8 if you are thinking you'll need additional I/O.

They use Boomslang for the patch harness, but suggested most local wiring places could do something similar as the header plug is readily available.

Of.course, the other big difference is that the Evo8 plug-in is discontinued. So, unless you find a leftover or used unit, there isn’t much choice now. An SL8 is a possibility too, though no wideband controllers and less I/O.