I'm not a fan of Mansory or G-Power, but I know enough about all the brands.

Mansory is the new kid on the block for the X5, but it looks like a G-Power on drugs.

G-Power parts will fit snug, but that is because it is a destructive installation - flanging of wheel arches, cutting, drilling, etc. But once the parts are on, they are on pretty snug. G-Power would like to get a stronger presense in USA. {{I removed the sponsorhip details from here - it has been discontinued, but they still so the G-Power engine tuning, so send me a note if you are interested in that}}.

Lumma, to me, looks the best. It's the most expensive because a lot of what you see is customized, not created and stocked by Lumma. The installation of Lumma is less destructive than G-Power as well.

AC Schnitzer, to me, keeps the "essense" of a BMW. It still looks very much like a BMW even after being fully kitted. There is a creater presense of AC Schnitzer here in South Florida because of CEC located in Miami.

Hamaan. I've seen the parts unassembled (laid out on the floor). They look really simple to install. Beyond that, I don't know enough about it.

Cost. Remember, we're talking about EUROPEAN cars with EUROPEAN modders. There is little care for big V8 engines. The Lumma kit, for example, was originally modded for the deasel engine, not the V8. That is why we clash with Americans, because Americans have a "need for speed", so they would only put the kit on a big engine. But seriously, is anyone going to race the strip in a SHOW CAR? Were also talking about a land that is riddled with Lambys, Fararis, Bentleys, Jags, BMWs, Audis, Aston Martins, Benz's, etc. "Money aint a thang."