Used his dyno for some dialing in of my one-off VW engine. Sonny is extremely knowledgeable, forthcoming and helpful. All around good dude; we will be back with various other hoopties for sure :)

Sonny has worked on my 06 lbz twice now (head bolt coolant leak and rotors/pads all around) and I am completely satisfied. I really appreciate that he follows all manufacturers instructions including proper lubrication and torque settings. Sonnys Diesel and Performance is my #1 choice for the Sonoma County area.

Sonny is the only one that will touch my cars. He is a constant professional and gives it to you straight. Loved the customer service and showing all the options. Appreciate the work youve done

Great service here, best in town

Where to begin? First of all I cold-called Sonny after a brief Internet search and left him a message to inquire if he could work on a VW Touareg Diesel, described my problem and gave him my call back number. A shot in the dark. Surprisingly, Sonny called back and we chatted about the details of my diesel motors EGR cooler related problem diagnosed by the VW dealers computer code reader. Sonny asked me to find out what the specific diagnosed code number the VW dealer had come up with so that he could research more precisely what the problem was. Sonny specifically said that he wasnt able to work on my car but he would get back to me. As with anything in this world of short attention spans, distance diagnostics and with someone who told me that he doesnt work on VWs, I was not expecting anything more, certainly not a call back. However, life can be surprising. Sonny called back the following day and after doing his research he explained in comprehensive detail what parts needed to be replaced and why. The local VW dealer in May had replaced the EGR valve but not the cooler. It turns out that if the VW mechanic had dug a little deeper he would have realized that by replacing the cooler, the EGR valve would have been included as a unit in the initial repair. So, as it turns out, I paid twice to resolve the initial problem. Now, the cooler needs to be replaced. Sonny, not only helped me understand my cars problem but took the time to look through his resources, think about the problem, come up with a solution and conveyed all of that to a lay person. Im incredibly impressed with Sonny to have taken the time to do this to help me out without renumeration. It shows that Sonny is passionate about what he does and Im sure that work ethic runs through all the diesels he services . Im buying a Cummings engined vehicle next time so that I can patronize Sonny Diesel Performance in the future. A super interesting and knowledgeable person and undoubtedly a fantastic problem solving mechanic! Thanks you Sonny. I hope we can meet sometime.