I've heard this statement before and, unless there's some seriously fuzzy math involved, can't understand how a $1,300 Howell kit and a $300 Motorcraft of $400 Holley kit are "about the same cost".
A Howell kit isn't the only choice, and Howell wouldn't be my recommendation anyway. Howell uses the GM throttle body system and
ECM common to a multitude of GM engines from the mid 80s to the 90s. There were different throttle bodies and different injectors depending upon the engine it was used on. A GM 4.3L V6 is quite similar to our 4.2L so you can use components off of them, or just take what you can find off of other vehicles as long as you end up with an ECM from a 4.3L engine. If you put together the system from parts off of a junk yard vehicle, purchase a new fuel pump (one off of a mid 90's Crown Vic is perfect), buy a speed sensor and an adapter plate to bolt the throttle body to your intake, then you can indeed put together a TBI system, better than Howell's
for about the same cost as buying Motorcraft carb and associated jets/parts to get a good tune.
What Howell offers, which is absolutely necessary to people in California, is a system that has been tested and contains tags to meet EPA requirements. As far as I can tell the only part they furnish unique to their kit is the adapter plate (Howell doesn't sell it apart from the set). Everything else is either a common part, or a refurbished part from a GM manufacture throttle body system. What Howell doesn't do is control the ignition through their setup (for reasons I really don't understand, but I'm sure they have one). In my opinion you lose a great benefit of having a Fuel Injection system if you don't let it advance/retard your timing and provide a tuned spark for your engine.
If you put a system together yourself you can use the feature already built into the GM ECM to control your spark. You can also use a knock sensor, an optional item which Howell also doesn't use, to retard spark if you start getting engine knock, and you can install a speed sensor to allow the appropriate fuel and spark for decelerations and other engine conditions, also something that doesn't come with the Howell kit. But, you need to be willing to assemble all the part and pieces yourself usually from different sources, remove unnecessary wires from a used harness (which may involve some soldering and connections), rebuild a throttle body, and follow some simple procedures for initial startup and setup. If you are willing to do those things and forgo the tech support that Howell can offer, then you can save yourself about $900. The choice for me was pretty easy (getting a system for $900 less that functions better than a kit for me was a no brainer).
There's no fuzzy math involved, just some work and effort. My costs for a throttle body system, including the $70 I spent for an ALDL to USB connector cable to be able to read and trouble shoot the system, was just over $400 and that included purchasing new the speed sensor, knock sensor, ignition module, adapter plates, throttle body rebuild kit, fuel pump and filter, IAC valve, and the connector cable I mentioned. Everything else came from the junk yard.
BTW, if you do it yourself you will use the same
throttle body, ECM, sensors, injectors, connectors, fuel pump etc. that Howell furnishes in their kit!