In all honesty, the factory airbox is really well designed and flows great with a few minor modifications and a decent panel filter.
Biggest issue is these cars run pig rich from the factory. It's a shame, because with a decent tune you could probably see significant gains from just afr tuning. The only company that even offers tuning for these cars will only sell you THEIR tuned PCM which makes it a bit cost prohibitive for what you actually get.
This is one of the biggest reasons I got rid of my car. So much potential, but so few options. Sad, because I really loved my Genesis.
Yeah, if there's no way to run the intake out of the engine bay, the stock box is the best bet to keep intake temps down. Like you said, just modify it to optimize airflow. Definitely the K&N drop in filter and remove the flap, and maybe replace the stock intake tube with a smoother one that doesn't change size. Or ate least changes size in the right way(think speedstack).
Just about every car runs rich at wide open throttle from the factory. WAY RICH... They are designed that way as a safety measure. The super rich AFR burns a lot cooler than 14.7:1, theoretically preventing the engine from burning itself up. That said, there are a good amount of gains to be had in leaning out the mixture.
You don't need a huge
aftermarket to see some serious gains. Just the right
mods; intake, exhaust, tine, tires. I know every car is different, but if I can get decent gains in a Toyota Avalon 3.5 liter v6, there's definitely more than hope for the 5.0 liter Genesis.
Avalon Stock: 268 hp/ 248 tq to the crank. Estimated 220 hp/ 210 tq to the wheels.
Avalon with K&N "cold Air"(actually short ram) intake, secondary cat delete, racing mufflers 93 octane. Dyno'd(hood up) at 237 hp/ 227 tq to the wheels. Ran a 15.1 sec 1/4 mile at 92.8 mph.
Avalon with DC sports (actual)cold air, headers, 2.5 inch dual exhaust w/xpipe, tune(vvt-i, timing, afr), summer tires, 93 octane. Made 311 hp, 265 tq to the wheels. Ran a 14.2 sec 1/4 mile at 100.7 mph.
I know headers are a tall order. Honestly, I don't know if I'd ever get them again in a daily driver. LOUD, and not too much gained with the rest of the exhaust unrestricted. Only gained .1 second and 2 mph in the 1/4 mile with the headers.
