I have FMF "powercore" aftermarket performance exhaust systems on all of my Yamaha dirtbikes, and a DG preformance system on my Yamaha quad. All of them four strokes of course.
The one thing they have in common is the inter baffle. They are ALL the free flow design, like old glasspacks.(I know, as I repack them all the time)
Now we can't argue that performance gains are what these manufactures are after, not necessarily sound. And all of them have a straight threw baffle, the same diameter as the header pipe.
I made my own baffles from a sheet of expanded metal from Home Depot, and cut the ends from some 18 ga. file cabinet doors. Wraped them with the same packing material I use for the other mufflers.
I LOVE THE SOUND I NOW HAVE! and imaginary or not, I beleive the acceleration is better.
Thought I post a couple pics showing the stock baffles side by side with mine.
