You can Peek in the wall, hiding from bullets. This script's code originally came from the Great Theft Car TC for San Andreas. Credits to Johnix (moddb.com) for creating the Great Theft Car mods.

To peek on the wall use N, to release N again.To shoot, hold the RMB and start shooting. And another feature, you can move along the wall, to do that, after peeking press Q or E to move along the wall.