Well, I don't see why you are trying to talk him out of it, if he wants to lift his Jeep some more then good for him, he should do it. Quite frankly you don't see the need for yourself to go up much higher than you are now, but he does. Some people just want a bigger, more aggressive looking ride, and there is nothing wrong with that.
O, I know people running much bigger than 33's on a D30. i.e. 35's and 36's.
As for the original poster, the thing is at 6 inches of lift the angles on short arms are too steep. This creates a horrible ride, and can wear out bushings prematurely, and even do damage to brackets should a bump or ditch be hit at the proper angle. (I know because I hit a ditch at less than 10mph on 4.5 and mangled a LCA bracket. You do not want to be offroad should a bracket break off and you need to get out of there, thats a hefty towing bill) If you want ride comfort, go for either drop brackets or long arms. Drop brackets will make the angles on the arms less severe and make the ride a lot smoother. Long arms you have to worry about possibly welding, new crossmembers, and also cutting the stock unibody side brackets off, which means there is no going back if you don't like it.
Now as for brands, I recommend Rubicon Express with drop brackets, and Old Man Emu shocks. This will give you a comfortable ride, but its a bit pricey. If you are looking for long arms, search around for the pros and cons on different brands like RE, T&T, Clayton, RK, Full Traction, etc.
You will need an SYE and new driveshaft for this amount of hight, as well as shims to fix the pinion angle. And as for steering, you will at least need a drop pitman arm. Don't forget about things like brake lines, sway bar links, bumpstops, trimming to fit the 33's, as well as backspacing, trackbar should generally be included in the kit, etc.
(it still spins the same way)
