I've ridden with guys that had the Penland Big gun on their bikes, and I have a full HMF with no silencer. Mine was noticeably quieter; I couldn't hear my bike when they were around me in the woods. HMF is suppose to make more hp under the curve, as well. Go figure.

 

No duals available for the P-650/P-700.
I am surprised "Wires" thought that the NYROC mod was loud! I find it mellow. Stay off the throttle, and you can still get "stealthy". I did the 6, .375 holes. My P-700 is not real loud and obnoxious. Wires did you do the same? 6ea.,.375 Holes?

 

I did 8, 1/2" holes., and then cut out the rear packing.

What is the size of the tailpipe on the Prairie after the packing is removed? The Arctic Cat ends up being 2" ID.

What I find that is on trails where you are at constant speed (i.e. 15-25 MPH), the drone tends to get to me. But an interesting thing though: The stock Grizzley makes the same amount of noise as the Nyroc mod!

If you're not doing the constant speed thing, then I didn't find it bad, it was just the drone when running constant RPM. There is a huge difference in sound from the 1" tip to the new 2" opening. I took it to my dad's place, and got bitched at for spooking the cattle! I mad a quick hack out there -- 2" pipe, with the end crimped to about a 1" equivalent opening, and it really makes a difference in noise.

I figured I'd use the packing when doing the family excursions, and then pull it out when the boys go out to play. [img]i/expressions/face-icon-small-wink.gif[/img]

 

My Supertrapp IDS-X with 12 discs is quiet and works well, too. I have to agree about the Grizzly exhaust tone; when you're behind one, the sound is annoying.

 

It's annoying when on it. That single cylinder 660 is rather harsh sounding.

 

I drilled 3 3/4" holes through the first two baffles then drove a 1/2" rebar through the last one. (couldn't locate a 12" bit) I then drilled 3 1" holes in just the first baffle and cut out the guts to the spark arrestor leaving the 1" pipe. I like the sound and love the performance increase.
What noise increase could be expected if I were to cut out the 1" pipe going all the way to 2"?

 

Can someone direct me to the Nyroc Muffler Mod? I've heard about it alot, but don't know what's involved[img]i/expressions/face-icon-small-happy.gif[/img]

 

I just PM'd you

 

I'm thinking it's about 50% louder. It's got more "boom" than stock. It's not bad, just the drone at constant throttle wears a bit.

 

I live in a small town and ride around my 1 acre yard a little ( ya know when I need a fix) so I think I will leave the 1" outlet for now.