Re-post, from What tuner to buy,

I studied on this same issue for 4 months before I decided. With so many dealers and variations to choose from it is a big decision and an investment that you want to make only once. I had a couple of issues with my DPF and then my DEF and really don't enjoy being 3-4 hrs from home towing a 5er with family and the truck telling me there is a problem and I've gotta get help within 150 miles, not fun and plenty stressful! Now I'm not dissing any vendors as most all the products I read about on some of the sites (although this site is the best one) are all capable of getting the job done, I made my decision based on

1. Customer service

2. Product reliability

3. First-hand knowledge of the product by the vendor

My choice was Double R Diesel, Ray and JJ (I think) answered all of my questions both on the phone and emails quickly and let's face it, not everyone is a diesel mechanic including myself, but this vendor took the time and patience to help me understand an educate me on this unit. They not only sell the MM3 units but they install them and test them on their own vehicles! The tunes are made for your truck for your needs so you receive what you want, not what a corporation thinks you want. I'll admit, I was nervous about doing this modification to my truck, I'm not independently wealthy and didn't want to make a "hotrod" out of an expensive vehicle just because I was having a midlife crisis! I wanted and need a durable, reliable vehicle that will give me years of service.

When I did the install of the unit and exhaust and it went together with no issues, thanks going to Ray DRD and his videos on the website. I did get a little confused when I was loading the files to the ECM and called Ray for guidance, it went to voicemail and I left a message. Meanwhile, I figured out the problem and got it finished. Within 30 minutes of my call to Ray, I was taking it out for its 30-40 mile learning drive, and Ray returned my call. He apologized for being busy and missing my call, I know hundreds of people that wouldn't even return a call after 30 days let alone 30 minutes! Just goes to show the sincere integrity of a man/vendor that stands behind their customer service. To say I'm impressed with Ray and DRD is an understatement. Point in closing, do the research, not only of the product but of the vendor who sells the product and then make your decision. God Bless....