What is the best way to change a player's gravity? [Un-answered]

local Tool = script.Parent
local Character
local Gravity = 0.75
local bodyForce

GetClass = function(instance, class, recursive)
    local children = {}
    for _, child in pairs(instance:GetChildren()) do
        if child.ClassName == class then
            table.insert(children, child)
        end
        if recursive then
            local result = GetClass(child, class, true)
            if result then
                for _, v in pairs(result) do
                    table.insert(children, v)
                end
            end
        end
    end
    return children
end

local createForce = function()
    local TotalMass = 0
    for _, part in pairs(GetClass(Character, "Part", true)) do
        if part.Name ~= "Handle" then
            TotalMass = TotalMass + part:GetMass() * 196.2 * Gravity
        else
            TotalMass = TotalMass + part:GetMass() * 196.2 * 1
        end
    end

    if bodyForce then bodyForce:Destroy() end
    bodyForce = Instance.new("BodyForce", Character.Torso)
    bodyForce.Name = "GravityEffect"
    bodyForce.force = Vector3.new(0, TotalMass, 0)
end

local onEquipped = function()
    local Player = game.Players:GetPlayerFromCharacter(Tool.Parent)
    Character = Player.Character
    Tool.Handle.CoilSound:Play()

    createForce()

    Character.ChildRemoved:connect(function(child)
        if child:IsA("Hat") then
            createForce()
        end
    end)
    Character.ChildAdded:connect(function()
        createForce()
    end)
end

local onUnequipped = function()
    if bodyForce then bodyForce:Destroy() end
end

Tool.Equipped:connect(onEquipped)
Tool.Unequipped:connect(onUnequipped)

This is a script I made for a gravity coil but it doesn't work like I want it to. I want to make a gravity coil that makes all player's go the same height when they use it, but hat's always seem to... well, not make that happen. What is the best way to make it so that no matter what, people will go the same height with the gravity coil and hats won't effect it?