Yes,some people invert them,when you move the engine off the thrust line you will probably introduce some or more cross coupling,such as increasing the speed causing the plane to go up or domn in pitch instead of neutral,lot of people aren't aware of this because they didn't fly at the thrust line to start with,just assumed the plane was supposed to fly that way.Some brands of the items you are adding come with a hatch on them.Any or all of the named items for the cowl,each builder does it different.Also other cowls work nice,Laser is one I've seen a lot on the 4*.