To install Race Tech Emulators, you will have to remove the forks from the bike. There is some "machine work" that needs to be done to the damper rods, which are bolted inside the bottom of your fork tubes, so the forks need to be removed. (The metal work can be accomplished with a good, electric hand drill and a sharp 1/2" drill bit. I paid a friend to drill the holes with his milling machine.).
You will also need to cut down your fork spacers to allow for the extra space the emulators take up inside the fork tubes. Your Sonic Springs will be shipped with a length of PVC tube that you will be instructed to cut to the appropriate length for spacers. I chose to reuse the OEM metal spacers and I recut those to the appropriate length to allow for the height of the emulators, (the extra space they take up), and to give me the proper preload to the fork springs during reassembly.
What weight fork oil you choose depends upon what type of riding you do the majority of the time.
We both weigh about the same.
I will share my experiences.
First, here is a thread on changing oil and springs: HERE
But, I think a better written description, (with photos), of how to remove the forks to work on them is HERE
Since doing the above spring work, I have installed R.T. emulators, (you can see them in the Fork Seal tutorial.). I have tried 12.5wt oil, 15wt oil and recently just changed to 10wt oil. The 10wt oil is where I am most happy with the performance of the bike. I also prefer the Gold Valves adjusted to "1 1/2 turns" instead of the factory "2 turns" of preload on the spring.
I ride fairly beat up roads here in Maine and Québec and New Brunswick, Canada. I try to find back roads; dirt roads to ride. The above setup, (Sonic .90 springs and Race Tech emulators), coupled with my Hyperpro rear shock provide me with the performance that I need to handle the surfaces that I ride on.
Although not the prefect solution, the Race Tech emulators do help with high speed compression surface irregularities, (pot holes.), over the OEM setup Suzuki provides. Dialing in the setting that works for you, takes some patience and experimentation.
Once installed, to adjust the emulators, you do not have to remove the forks from your bike, but you will need to remove the fork caps, spacers, washers, and springs to be able to "fish" the emulators out of the bottom of your fork tubes, (I use a welding rod with a "barb" bent into the tip to make "hook" to retrieve the emulators.). When removing the above items, work slowly so that the existing fork oil has time to drip and run back down into your fork tubes off of the parts you are removing.
VERY IMPORTANT NOTE!
: The very first time I adjusted my emulators after installing them, I had a "Mortaine Moment" and removed both fork caps without jacking up the front of the bike. That is more accurately described as an "Oh $hit" moment as the second of the two fork caps pops off as it nears bearing unthreaded during removal because, the whole weight of the front end of the bike is bearing itself on the fork caps. What happens? The fork cap pops off and the front of the bike does an irrecoverable, front end dive, until it bottoms out. Scared the hell out of me. But, no damage done. Lesson, jack the front of the bike up when removing fork caps!
Once you remove your damper rods from the fork tubes, you will need to drill or mill 1/2" holes through the rods near the bottom. There are 6 ("compression") holes in my damper rod.
Braze the small damper hole closed. You can use Mapp Gas and a brazing rod purchased from Home Depot or Lowe's. Before brazing, remove the plastic oil ring from around the upper neck of the damper rod to prevent the ring from deforming or melting from the heat generated during your brazing job.