hitch question

I had a 2009 Chevy Traverse (2000 lb tow) without the factory tow package and a 2012 Traverse (5200 lb tow) with the tow package and there was a huge difference. I bolted an aftermarket hitch on the 2009 but there is far more to it than that. Suspension didn't sag as bad on the 2012, it had the tow/haul selector. There isn't a problem with bolting on the hitch itself, the problem is with everything else that cant be upgraded. I would get the factory tow package.