Generation IV External Engine - New dynamax vt muffler

http://www.dynomax.com/mufflers.php?muffler=vt

These seem like a great idea. That little spring and flapper valve would create a little backpressure but to have a straight through design without droning seems brilliant.

Does anyone have experience with or heard these?

I wonder how long until the spring fails or the resistance changes.

Good point. More than likely, as the spring weakens, the flapper valve will just stay open easier, since it appears to be a fail safe design. I think they're offering a lifetime waranty. My super turbos from the early 90's have never given me trouble. Still tempted. Any other thoughts?

Best sounding muffler on the market. All I use, because none of their Ultraflo series drone anyway...?? Give em a shot.

Had them for a weekend and sent them back. They do sound good when you floor it, but transitioning from coast to part throttle and back, they rattle like a bunch of aluminum cans are dragging under your vehicle.

On one note to point out though, I was told that I had a couple of mufflers from the very first batch that were sent to Summit and the valve angle had been redesigned to address the rattle issue.

Thanks for the feedback. Maybe I'll call walker and ask about this issue. Sounds like the safe bet is ultraflow.

Had them for a weekend and sent them back. They do sound good when you floor it, but transitioning from coast to part throttle and back, they rattle like a bunch of aluminum cans are dragging under your vehicle.

On one note to point out though, I was told that I had a couple of mufflers from the very first batch that were sent to Summit and the valve angle had been redesigned to address the rattle issue.

I had the exact same problem so i took them off.