For those that doubt an intercooler would make a difference to a standard HD FT then try going uphill on a clear crisp cool winters morning ......the engine will if anything like mine feel crisper and pull harder simply because the ambient air is cooler and denser , it is noticeable .
It's difficult to appreciate on a moving vehicle how efficient a good intercooler is ........I often have big 300hp plus tractors on a dyno and making the engine work hard .
A good indication is that you can't put your hand on the inlet side of the intercoler as it is too hot , the outlet side while warm is comfortable to hold your hand on......in fact my preferred hand warmer on cold days when dynoing .
Remove EGR from the equation and with a good cooler you can get back to ideal inlet temps.