You already have that. A bone stock 4Runner will get you to any trailhead anywhere. Without any mods at all you can take that truck 99.9% of the places it's legal to drive, including some places that don't look like roads at all. You don't need to mod, you just need a little more confidence in yourself and your truck.

I like my OME springs - they're a great option if you decide to lift the truck, and ride much better than stock on the dirt. It's a bit of a rough ride on the pavement, and it'll raise your CoG and wind resistance, making for worse handling.

Skip the K&N intake. You'll get better returns by replacing the stock intake tube with aluminum or stainless and heat-wrapping it.