I have tried a few different set-ups and thought I would pass along my experience for other to build off of.
I have tried 3 different springs in the primary clutch. All from SLP - the black/yellow, black/red and black/pink. These all have a 120 start rate and engage at around 4,000 rpm. The engagement is much smoother and more linear that the stock spring, and works better when boondocking IMO. I haven't experience any bog at the lower engagement RPM and all have held peak RPM well. The springs had the following effect on peak RPM:
Black/yellow (120/310) peak RPM was about 50 less than the stock spring.
Black/red (120/320) peak RPM was about the same as the the stock spring.
Black/pink (120/340) peak RPM was about 100 higher than the stock spring.
I think the SLP springs peak rate is overstated when compared to the stock spring as the SLP 120/320 spring had about the same peak RPM as the stock spring (140/290?) - at least in my sled.
Shift assist - I lost about 100 rpm after installing the shift assist. I don't know if this was due to less spring compression because of removing the the 2 black spacers or if the secondary was just shifting out faster. Overall, the secondary was smoother and held a more consistent peak RPM.
Cutler 65-75 grm adjustable wts. Running the bare 65 grm wt without any set screw - just an empty hole all the way through the wt - added about 150 rpm over the stock 68 grm wts. Shift profile feels the same and the wts work very well.
SLP 44/36 helix - this helix is great in my M1000 but it didn't work for me in the M8. It felt like I was in too high of a gear and my rpm's were noticeably lower. This helix may work for some of you that claim your running 8500 rpm with the stock weights, but it was too much for my sled.
SLP can - according to my scale it is 11/lbs lighter than stock which is what SLP advertises. Excellent fit and finish. Dimensionally the can looks exactly like the M1000 can, but according the SLP the internals and different and it was designed specifically for the M8. It is also 2/lbs lighter than the M1000 can. The exit down pipe sticks out about 1/2-3/4" below the snow deflector. I've noticed this on the M1000's with the SLP single set-up also. I don't know why the designed it like that, but I'm sure they had a reason. Performance so far has been flawless and I have seen a slight increase in RPM. However, I don't know if this was due to the can or not as my sled has slowly been gaining rpm as it gets for miles on it. Below 6000 rpm no one will suspect you have a can on as the sound level is very stock like. At higher rpm they will suspect you have a can on, but won't be sure because it has a throatier growl, but doesn't produce much more noise that the stock can. This isn't the lightest can available, but is probably is the quietest of the aftermarket cans.
Hope some of this info is useful...
I have tried 3 different springs in the primary clutch. All from SLP - the black/yellow, black/red and black/pink. These all have a 120 start rate and engage at around 4,000 rpm. The engagement is much smoother and more linear that the stock spring, and works better when boondocking IMO. I haven't experience any bog at the lower engagement RPM and all have held peak RPM well. The springs had the following effect on peak RPM:
Black/yellow (120/310) peak RPM was about 50 less than the stock spring.
Black/red (120/320) peak RPM was about the same as the the stock spring.
Black/pink (120/340) peak RPM was about 100 higher than the stock spring.
I think the SLP springs peak rate is overstated when compared to the stock spring as the SLP 120/320 spring had about the same peak RPM as the stock spring (140/290?) - at least in my sled.
Shift assist - I lost about 100 rpm after installing the shift assist. I don't know if this was due to less spring compression because of removing the the 2 black spacers or if the secondary was just shifting out faster. Overall, the secondary was smoother and held a more consistent peak RPM.
Cutler 65-75 grm adjustable wts. Running the bare 65 grm wt without any set screw - just an empty hole all the way through the wt - added about 150 rpm over the stock 68 grm wts. Shift profile feels the same and the wts work very well.
SLP 44/36 helix - this helix is great in my M1000 but it didn't work for me in the M8. It felt like I was in too high of a gear and my rpm's were noticeably lower. This helix may work for some of you that claim your running 8500 rpm with the stock weights, but it was too much for my sled.
SLP can - according to my scale it is 11/lbs lighter than stock which is what SLP advertises. Excellent fit and finish. Dimensionally the can looks exactly like the M1000 can, but according the SLP the internals and different and it was designed specifically for the M8. It is also 2/lbs lighter than the M1000 can. The exit down pipe sticks out about 1/2-3/4" below the snow deflector. I've noticed this on the M1000's with the SLP single set-up also. I don't know why the designed it like that, but I'm sure they had a reason. Performance so far has been flawless and I have seen a slight increase in RPM. However, I don't know if this was due to the can or not as my sled has slowly been gaining rpm as it gets for miles on it. Below 6000 rpm no one will suspect you have a can on as the sound level is very stock like. At higher rpm they will suspect you have a can on, but won't be sure because it has a throatier growl, but doesn't produce much more noise that the stock can. This isn't the lightest can available, but is probably is the quietest of the aftermarket cans.
Hope some of this info is useful...
