Aftermarket ECUs

Generally if you're going this route you probably don't need any guidance about how to do it. Here are a few aftermarket ECU options and some differences:

Megasquirt

Holley EFI

Haltech

Stock PCMMegaSquirtHaltech SportHaltech Elite 750Haltech Elite 2500Holley Terminator XHolley HP EFIHolley Dominator
Cost of ECM~$100 - $300 for tuning tools~$600$1,187$1,200 for ecu alone$1,950 for ecu alone$1,200 with harness and 3.5“ lcd$1,433$2,300
Cost of Wiring Harnesses Uses factory 3800 harnessextra $224 for premium harnessextra $255 for premium harnessComes with the harness
~$700
Can buy as a kit
>$700
Harnesses sold individually
Ease of harness install for 3800Plug and PlayRequires custom harnessPlug and PlayRequires custom harnessRequires custom harnessWill need some modification or custom harnessRequires custom harnessRequires custom harness
Ease of useModerateDifficultEasyEasyEasyEasyEasyEasy
ReviewsGood enough for most peopleDifficult to put together, but a lot expandability. Pretty dated nownot great State of the art. Created in Australia though support can be trickyTerminator X is a lot like HP EFI but with a few less bells and whistlesSimilar to Dominator but with less inputs/outputsDominator is basically the state of the art. Holley is very reputable
water-proof?yesnonoyesyesnoyesyes
Wideband auto-tuning supportnonono?yesyesyesyesyes
MAP limits for speed density tuning1.4 bar 22 psi for ECM's internal MAP sensor 5 bar5 bar7 bar
drive by wire supportSome PCMs yes yesyesyes x2
Transmission controlyes yesyesyesonly with “Terminator X Max”noyes
anti-lag / launch control built inno yesnoyesyesyesyes
CO2 controlno nonoyesyesyesyes
Boost by Gearno yesyesyesyesyes
Flex Fuel sensor supportnot with a 3800 PCM yesyesyesyesyesyes
Stages of nitrous control0 116 48
fuel injection outputs6 61-61-8up to 8up to 812 “peak” + 12 “hold” = 24 injectors
Ignition OutputsOEM 684 ground
Can expand with CAN IO Module
4 12v or ground PWM
Can expand with CAN IO Module
20 12v PWM
16 ground PWM
Can expand with CAN IO Module
Digital Outputsnone 28 0
Analog inputsnone 10204413 “multi-inputs” + 30 sensor inputs (0-5v)
injector stages for fueling0 4
Internal Data Loggingno yesyesnoyesyes
Known Odditiesoh boy, yes not potted
can't use external battery charger with ECU connected
can't use external battery charger with ECU connectedcan't use external battery charger with ECU connected