The experience I had with them wasn't the worst, but it certainly wasn't the greatest either.
At the beginning of my modding phase I went to Modbargins because it was the first resource I was introduced to. I'm not going to name which sales associate it was, but they were not helpful at all. I bought a few things from them all at once but it was one item the caused me a lot of frustration. I bought Blackline style LED tails and supposedly they claimed it wouldn't cause codes, errors, flickering, etc. Sure enough after my install I got ALL those issues. I emailed them and explained to them the whole process, description and how I installed them. And guess what?! They blamed me that it was my fault that it caused all that. I told them I did exactly what the manual described. Long story short, they played dumb that they didn't know it needed an anti-flickering module and they would charge me an additional $30 plus install for it. I refused bought the kit from JLevi aka SVC. That's one of the well known problems with the LED tails and they didn't know? JLevi, LTMW, and Beast Power all knew that was a common problem with them, why didn't they? And they're also BMW specialist? I felt like they tried to play me for a fool and just not tell me.
Like a said, it was a good experience, up until they pointed blamed on me. Good thing I didn't pay with a Credit Card and payed with cash.
If you're in So Cal, please just stick to LTMW. They know our vehicles inside and out. I've gone to them since then and have been more than pleased with all of their services and customer service.