I feel like it'd be a great idea to swap these two perks so "Server Banner" is at Level 1 of nitro boosting and "Custom server splash background" is at Level 2.
Why? Simply because I think the bigger the server you have, the more likely you are to get use out of the custom invite splash visuals.
This is in comparison to if you run a small private server (with less than ten people and so no way of getting to Level 2 easily) you'd probably rather have the custom server banner to spruce the place up a bit.
I feel like this small change would be *huge* to people in smaller servers and would thus ultimately result in way more Nitro purchases.
P.S. I'd also love one perk of Nitro Boosting to be more pin slots in the same way we get more emote slots. Thank you. <3