I would like to know what the best performance exhaust for the Grizzly 660 would be. Noise is a primary concern because we ride on forest service trails. I would like an increase in the low to mid powerband. Any input, including jetting set-up would be greatly appreciated.

 

I have a 04 grizz I have an HMF exhaust. that pipe gives great power but the quality sucks and it's really loud even w/ the quiet core. the best pipe on the market for utilty quads is supertraps ISD-X or the ISDII they are fully tunable and the discs are inside the pipe so they don't get cloged. the white brothers pipe is also good but the discs are external.

 

Thanks much for your imput!

 

Hi. just purchased a billet aluminum end for the pipe on my 04 Grizz. works ok opens up pipe to 2" from 3/4". hard to believe but it realy does work. bought it off of EBay for 37 Bucks buy now deal, maybe I should of bid but what the hang. next is drilling the restricter inside but I need a very long drill bit. theres an article to read.on how this mod works on another forum . but I need to email you the address . can't print it it like swearing. with the billet aluminum end u can always put it back to stock when u want to be quiet. so for $40 bucks and a drill bit and its as good as a pipe.



First, we removed the muffler tail piece and spark arrestor.
Then we use a long bit to drill about 8, 1/2" holes in the last baffle wall of the muffler. Then we replaced the tail piece and arrestor. This mod did add a little snap without a large increase in noise.

Second, we took the muffler tail piece/exit hole and sawed off the end of the tale pipe and put a cutting bit over it and drilled the exhaust pipe out. The stock exit hole looks to be about 5/8 to 3/4" in diameter from the outside, but if you stick your finger in as far as it will go you will find that there is a pipe reducer inside of the tail piece that makes the final exit hole even smaller...about 1/2" or so!

After drilling out the small stock pipe end, we replaced it with 1 & 1/2" race car roll bar pipe and welded it on. Pete slid the pipe in about 1 & 1/2" through the piece and welded it. The spark arrestor will slide right over the pipe from the back and mount right back on as it did before.

Making the outlet hole bigger did change the sound making it louder when accelerating, but giving it a nice low rumble at idle.

As far as performance goes...it works! The bigger outlet hole made all of the difference! Both of the 660s will now wheelie in 4x4 HIGH! Thats right...I dont mean 2wd low, or even 2wd high, but in 4wd high! This was done by standing up and pulling back on the bars...no sitting back on the seat. Pete played around with it a little more than I did, but even after the road got a light dusting of snow on it Pete was still able to get the front end up 6-8" or so. Both of these machines have 27" tires on them.