A higher calibre gun, or at least a way of editing guns in a more advanced way, guns at the moment fire like Lazers they shoot in a straight line, real guns however, are unlike this, unless velocity is high enough your bullet, or shell will gradually drop, this varies from weapon to weapon, and it's the same with side to side accuracy, this can be a good thing as you do not need to squint at the target to see if your aiming reticle lines up, you can just fuel in the general direction, bullet spread will do the rest.

Calibre should also be editable, or a large calibre cannon should be added, it's shells would have a drop effect and would explode on impact, a cool thing to have on ground attack planes, AAA,Tanks and ships, smoke effects could even be added with large flashes and a loud booming sound effect like when a missile explodes in the current form of the game.

Life would be a lot easier if tracer emitted light, like the actual lights then if firing in the dark you can see the projectiles better.

This would be a good addition as the only was you can create a large calibre howitzer is through fiddly complex XML or the fiddly procedure of trying to build a detacher gun or a gun with rocket pods for instance.

Also, if this was implemented it would be nice to see an armour option for the fuselage block that added loads of weight but increased survivability of your plane (so no more OP biplanes destroying modern jets with miniguns! No sir!)

Just a thought...