If your friend has two of these he is in big trouble. In CA you can not have a detachable mag and a pistol grip. I would pass and tell your friend to keep them hidden or get them out of CA.
Assault Weapon "Evil Features"
California Penal Code Section 12276.1
(a) Notwithstanding Section 12276, "assault weapon" shall also mean any of the following:
(1) a semiautomatic, centerfire rifle that has the capacity to accept a detachable magazine and any one of the following:
(a) pistol grip that protrudes conspicuously beneath the action of the weapon.
(b) thumbhole stock.
(c) folding or telescoping stock
(d) grenade launcher or flare launcher.
(e) flash suppressor.
(f) forward pistol grip.
The following definitions apply to terms used in the identification of assault weapons pursuant to Penal Code section 12276.1:
5469 (a) "detachable magazine" means any ammunition feeding device that can be removed readily from the firearm with neither disassembly of the firearm action nor use of a tool being required. A bullet or ammunition cartridge is considered a tool.
(d) "pistol grip that protrudes conspicuously beneath the action of the weapon" means a grip that allows for a pistol style grasp in which the web of the trigger hand (between the thumb and index finger) can be placed below the top exposed portion of the trigger while firing.
Basically it breaks down to a single choice and you have to decide what is more important to you. Are you willing to make some ergonomic sacrifices in order to have a rifle with a standard operation magazine release or would you rather sacrifice a little speed when reloading so that you can have features such as a normal pistol grip, forward grip, and collapsible stock?
I want to have a normal looking rifle
Then you will need to have a "fixed" magazine. Buy the Prince50 or the Bullet Button magazine lock kit and then you can have all the other evil features you want. It will take a little longer to load. If using the Prince50, you will have to pull the rear takedown pin and top-load into the fixed magazine. If you go with the Bullet Button, all you have to do is insert a bullet tip into the lock, drop out the fixed magazine, and insert another one in it's place. You can only use 10 round magazines in a fixed-magazine rifle.
I want to have a normal magazine release
Then you will have to build a "featureless" rifle. Typically this involves using a standard A2 stock or any other non-folding, non-collapsible stock, a non-pistol grip such as the MonsterMan Grip or the U-15, and replacing the flash-hider with a muzzle brake or using a barrel with no muzzle device at all. The bonus of a featureless rifle is that you can legally use 30 round magazines if you had them in your possesion before the ban took effect in 2000.
More useful links:
The Off List Lower "Cliffs Notes"
A California AR/AK "Series" Assault Weapon FAQ
The Office of the Attorney General Assault Weapons Identification Guide