I have looked at MRD's pipes for my 07 YZ450F, they are priced to sell but are they any good? For those who may have them, where did you notice a difference in the power delivery with this set-up and how does it sound!? I like the idea of having a more "hand made" vs. stamped out exhaust (for less money too?) IF they are quality. I'm looking to replace both the muffler and head pipe... I've heard a lot of people really like the DR.D systems for these bikes but they are more of a financial commitment lol. Right now I'm thinking FMF mega-bomb/power core 4 (I've read that the PC4 isn't much different than stock as far as performance?) A DR.D NS-4, which I know nothing about other than people seem to like their products. Or the MRD set-up which would be way less expensive than either of the larger manufacturers offerings. This bike is used exclusively for the sand dunes so which ever set-up offers the best performance on the top end would be preferred. Any thoughts or suggestions? Is their another pipe I should be considering for this application? Thanks.