A simple Tampermonkey userscript that lets you hide forum sections you don't want to see in the New Posts page. Simply add unwanted section names to the excludedSections array.

Spoiler - click to reveal

// ==UserScript==
// @name LFSForum_NewPostsFilter
// @namespace http://tampermonkey.net/
// @version 0.1
// @description Hide unwanted forum sections from LFS Forum's "New Posts" page.
// @author Lakyn
// @match https://www.lfs.net/forum/*/newposts*
// @icon https://www.google.com/s2/favicons?sz=64&domain=lfs.net
// @grant none
// ==/UserScript==

(function() {
'use strict';

const excludedSections = new Set([
'Off Topic',
'Vehicle Mods - Work in Progress',
'Vehicle Mod Reviews',
'Review archive',
'Rejected',
'Vehicle Mod Discussions',
])

var a = document.getElementsByClassName('FThread');
for(let i=0; i < a.length; i++ ) if( excludedSections.has(a[i].getElementsByClassName("ForumName")[0].innerText) ) a[i].style.display = "none";

})();

This is amazing, thank you!

Thank you for this, it had exactly what i was looking for.