This is a real world, by the seat of my pants, no dyno real life experience. My ride is a 2008 YZ450F. I have used Yoshi the most but have ridden PC and FMF…even Two Brothers. Now I am on a Yamaha and the first thought was DRD. But… One night (after a couple of cold ones) I was surfing the net and sent in a question on MRD’s web site. 9am the next morning I get a call, “Hi this is Dave from MRD, I would love to answers any questions you have about exhausts”. I was floored! Dave and I had a 15 minute conversation about what type of riding I do, how hard I ride and what I like and dislike about my bike. Never once before I purchased an exhaust was I able to call up DR. Yoshimoura or Mitch Payton to discuss my specifications. I usually get one maybe two choices from a retailer like Motosport. Dave finished the conversation by saying I have 3 specifications for my type of riding (race trails but practice motocross) but he has a favorite that he thinks I would love. Of course he explained that every system he builds his custom to the rider, his life time warrantee and also would send jetting specs for my elevation. For right over 400 I got a complete system with jetting specs. He told me exactly how it would feel. And can you believe it…it actually felt exactly how he said it would. I will never buy from anybody else! Why would you spend $500-$1200 on an exhaust and not get it custom made for you. You ‘all are crazy; MRD is the only way to go!!!!!!!