Cheat
Note: this only works with X-Wing Alliance v1.00!
As I was messing around with the settings of this truly awesome game I found a cheat/bug which you can exploit.
Press ESC during the game (favorably in the Concourse / aboard your Family Transporter). Go to the 'General Options'. At the bottom you can set the preset values for 'F11' and 'F12'. Now set the 'Beam Level' to Zero.
Note: This only works when you don't have a Beam Weapon installed ! (tnx 2 LoX)
When flying press your new-edited F11-key (or F12 whatever) and you're in for a surprise. The game seems to allocate energy for the Beam Weapon even if you don't have one installed - and since we set the Beam Recharge Level to Zero you are getting that energy added to your engines !!!
This will give you an edge especially with the slower ships (e.g. Y-Wing, CORT's ...).