True on cams if only upgrading to a 272, but most definitely not on injectors. OEM injectors take different latency voltage / scaling. Running a specific injector outside its desired voltage can cause a lot of engine problems.

Never install bigger injectors unless you adjust the tune to compensate.

 

Walbro 255 is drop in friendly. Do NOT change to an aftermarket FPR. The stock FPR works great on the walbro 255.

The biggest mistake someone makes when installing a Walbro 255 into their evo is they do not get an install kit and try using the OEM insulator over and its thinner, and it allows the pump to come out of the pump seal in the housing which causes pressure to be lost.

So make sure when installing the Walbro 255 to use the insulator in the install kit since its thicker and will keep the pump pushed up into the seal so you get a good seal.

I would recommend pushing the relief valve in also, the pump wont bleed pressure at high RPM and you will get 20% more fuel delivery or so.

It will require a retune if the pumps modified. If going from OEM pump to walbro 255 it also requires a retune.

 

the bottom rubber piece? All the install kits I see come with that, a piece of fuel line, a couple clamps, pigtail, and sock. I didn't think any of that was different than what I had. But now I'm curious.

 

Yes the black spacer that goes directly under the pump near the filter. It helps the cap push snug onto the pump keeping it pushed up into the seal. using the OEM spacer will result in the pump falling out of the seal and bleeding pressure.

You can use a piece of random rubber also assuming its submersible with fuel safe, but buying the install kit is the correct way to go about it. Whenever replacing a fuel pump, you should always do the filter also.

 

I had no idea. Good info.