I've been to Valley Muffler twice, and both times I left feeling as though I had spoken to a genuine, HONEST, and respectable (not mention knowledgeable) mechanic. Raymond Miera is a complete gem of a guy and has no ulterior motives when it comes to helping you with your car issues/add-ons.
The first time I came in I wanted to have an exhaust leak welded, but Raymond told me that the leak was so tiny that it was practically sealing itself as the metal would heat up after a couple minutes of driving and wasn't necessary to have work done on. This guy is so honest that he even turns down your money!
Time number two: I had multiple leaks in both my driver's-side and passenger side exhaust manifolds, and not only did Ray fix them to perfection, but he even agreed to do it for me when it meant he'd have to stay 2-3 hours after work to get the job done. Oh and he also gave me his CD consisting of awesome fingerstyle guitar tracks to listen to (and even take home and burn) while I waited for the work on my car to be finished. And not only did he complete the job in a timely manner, but he completed it to perfection.
If you're looking for an intelligent, hard-working and honest person to do work on your car, bring it to Valley Muffler in West Covina.