I did it-- Installed Black EPI secondary spring, using nyroc homemade spring compressor. Black spring is about 1 1/2" to 2" inches longer than stock spring. I thought plastic 2" cap on spring compressor was going to slip off when installing new spring (lots of tension) But it didnt. Bike neither gained nor lost any top end speed(feels exactly the same as old spring did.
I do notice more grab when accelerating(not a big change because 360 engine doesnt have enough ***** to apply any more power to the wheels. I also had two shims in the pulley(belt was super loose when I first dismantled, and only about 40 hours on machine) and removed both shims.(bike squealed a little bit in gear at idle, but is slowing going away. Probably worth it if I can get more power out of this engine, plus the extra belt life it is supposed to add--but did not make a major change.

I also performed NYROC exhaust mod---Didnt really work like it was supposed to------------- 360 muffler has welds on outside of muffler, 4 welds front to back(they can be easily seen looking at muffler---I cut back of muffler off and could not pull spark arrestor out!! seems last baffle is welded to the spark arrestor and I had to pry and force spark arrestor out enough to get a screwdriver in to use as a chisel to seperate baffle from spark arrestor (aggravating)needless to say i eliminated that baffle pemanently.

I then proceeded to drill holes with a 3/8" x 12" long drill bit. First hole and drill bit broke (its still in there)
Bought second bit and drilled 6 holes through 3 sets of baffles(careful because I got carried away and drilled one hole out the front of the muffler(more on that later). I reinstalled muffler end with brazing rods and a cutting torch(also fixed hole in muffler that i accidently drilled) and bike sounded exactly the same as before I did anything to muffler??? Cut back of muffler off again and this time I cut spark arrestor in the middle(shorter) and pulled out packing. I also took long drill bit and drilled a couple of holes up through muffler on engine side. Put back together and still is very quiet(disappointed although I was not looking for a lot of noise, I hope I opened it up enough that I will notice a difference when I install Twin Air filter and Dial A Jet (both should be here any day now.)

I tested for top speed with stock muffler, NYROC modified muffler, and no muffler---NO CHANGE!!! Bike will only pull 30 MPH at the top of my driveway!!

Hope somebody invents a CDI for this engine(it could sure use it)

Comments?? Questions?? Suggestions???