Yamadoo,
I went with the 128" Cobra (153 studs) about 3 seasons now. I mostly trail ride and IMO the Cobra track is great. I think the 128" is perfect for these sleds when it comes to 'all-around' performance, handling and ride. It def helped in the 'traction' department. With my 'add-ons' I was def struggling for traction with the 121" Ripsaw (even with 192 studs). I didnt like the feel of 192 studs as well (especially with the outside lugs studded). I love the feel of the Cobra track in the corners as well. I like to swing out the rear end at times and I believe the Cobra allows this. Dont get me wrong...you will get better traction out of a 136" and possibly better ride quality but for overall performance and dif of cost...I dont think you will be disappointed with 128" has to offer. After installing the 128"...my first ride out I did eat the snow flap bracket. I just left the bracket on there and bent it up (towards the front of the sled) to make sure the track/studs would continue to clear it. I tied/hung up the snow flap by taking a shoe lace from a hockey skate and wrapping it around the grap bar, drilled a hole in the snowflap and ran the lace through the hole and knotted it through a big washer in the inside of the snowflap. I wrapped the shoe lace with black elec tape leaving about 2" of the shoe lace free of tape so the snow flap could ride up and down on the lace freely. With the snow flap tied up I havent had any problems (as well as going in reverse or backing off the trailer).
