Fuel pump and Injectors

Hey Deevon,
Great question and you get what you pay for. My response is going to get a little detailed, here is some of my opinion.

Injectors
eBay is fabulous for knock off parts, when prices are a quarter of what the supplier sells them for in Japan.... Example by a reputable tuner website selling for sard brown tops $500+ and eBay special so much less ?.... Maybe a knock off or "made in the same factory" or same design, especially in sard and other popular brands. Why am I sceptical of an eBay 840cc injector when sard brown is a 800cc injector - sometimes small details show its a knock off (however may still work). I know of a guy running eBay specials, what I think is those injectors, and loves them.
PS sard does not list that injector for the 3sgte

Spray pattern
Injectors you can use almost anything that fits the hole. In saying that, sometimes wrong injectors still work, like running the wrong oil, you can get away with it 8.9 times out of 9 times or sometimes higher. Injectors are designed with spray patterns based on where an injector sits in the intake in relation to the valves that effects attomisation, and other design differences, small differences for the engine application; hence why the manufacturer lists for an engine

Impedance
Are you running a standalone ECU (that will run high impedance injectors), are you running a piggyback ECU (that will only adjust the signal by a percentage so need to match the injector size based on a dyno result) or are you running a factory ECU (low impedance).
PS The injectors you are looking at a high impedance

Response time
The ability for the injector to change its flow rate. Cylinders are super fast. Injectors that are super slow don't produce the best results. If you get genuine sard 800cc brown top high impedance that have a response time of 1.6ms compared to genuine sard 800cc dark blue low impedance injectors that are 0.75ms. However any injector may work for what you want.

Fuel rail
The biggest mistake for mr2 sw20 especially gen2 and less so gen3 is the biggest design flaw is in choke point / the fuel rail, fuel enters one side in a 4mm or 6mm bore and leans in cylinder 3&4. Upgrade your fuel rail, generally to a 8mm or 10mm rail (aftermarket top mount), and/or dual feed especially going larger injectors / more boost etc.

Flow tested
Regardless of what injectors you get, have them flow tested before putting them in the engine.

Fuel pump, you can check on walbro website if they are an authorised seller. If not it's likely an eBay "sard" "hks" "walbro" special that the guy who bought it will say it's original but the manufacture brand that the listing refers to didn't make it.

All of the above guide depends on your vehicle modifications and driving needs.