The conversion to EFI is not as simple as it appears at first glance. The Hollry Sniper system is a throttle body speed density system that starts around $1400 for the base Holley kit and depending on the kit can creep up to $1,800 or more.
The Holley system architecture is similar to the 1970's early EFI systems out of Detroit that used throttle body style injectors. Eventually (and eventually may not take as long as you think) either you or the car will outgrow the Holley system and you will want to migrate to a port injection system. That means essentially everything you have bought is unusable, a throw away or sold at steep discount.
It would be to your advantage to go the port injection route initially rather than 'down the road' so to speak. The price will be higher because you will need to source a suitable manifold, injectors, fuel rails etc. but you will eventually experience all those costs anyhow. The big difference is you will not have initially sunk the monies into the Holley system so the conversion will be less expensive by the price of the Holley system you did not purchase.
Holley's system uses a speed density fuel model, which is a very popular EFI fueling model today. Something to remember about speed density systems is that
they do not measure air mass they infer it based on a wide range of variables you specify in your tune file and they monitor in operation. Change your air cleaner, your heads, your cam, your compression, your cam phasing, the ambient temperature, the ambient air pressure and on and on and you will need to retune the EFI to get back to the smooth seamless operation you had after initial installation and tune. This is a big deal — especially at current tune prices.
If you use a Mass Air Flow (MAF) fueling model like Detroit uses on all modern EFI systems you don't need to do any of that because a MAF based system directly measures the air mass being consumed by the engine and fuels the engine accordingly. Many if not most of the F-1 cars today use this same system because of its ability to compensate in real time for a wide range of environmental change(s).
You're not F-1 but the same tuning issues apply and the most common are weather changes and altitude changes as the car goes to higher and lower ground. Of course don't forget the silly stuff like air cleaner changes.
Do your wallet a favor and tap the brakes a bit before financially committing to any particular system. Something to keep in mind also is that some EFI manufacturers will produce plug an play EFI systems that literally plug right into an OEM EFI wiring harness.
The OEM harness route brings reliability, robust protection and appropriate EFI signal shielding where required without any effort on your part. The EFI system does not care what size your engine is — you get to specify that during ECU setup. This means that if you think you might want to play around with power adders later, you can get a system that is already setup for power adders and just not enable the feature(s) you aren't using. Later if you want, it is literally a couple of mouse clicks in the ECU setup s/w.
Here is an example of what I was just talking about. It is a aftermarket system offered for supercharged 03/04 Cobra's. It supports, turbos, centris, roots, and screw blowers or no blower at all. It has traction control, nitrous support, engine failsafes for temperature,
oil pressure fuel pressure etc. It uses OEM Ford sensors, GM sensors or non automotive commercially available sensors so you don't need to buy OEM sensors that have been repackaged and repriced. Here is a link =>
03/04 SVT Cobra Plug and Play EFI.
BTW if you have never built an engine wiring harness, it is an experience you would like to have avoided if you knew in advance the headache that comes with it. P-n-P with an OEM harness has beauty and simplicity that is only visible after you have built your first wiring harness.
Take your time, look around, learn the technology and learn the systems alternatives before you spend your hard earned money. It will save you a few thousand dollars and lots of aggravation. FWIW I use a P-n-P system for all the reasons above.
Ed