HarleyTechTalk

Out of my depth obviously, didn't realise the gen2 ment a physical difference in the shaft.

Be following to learn more obviously, saw a chart for the 528 133T 125HP but no other parts info.

I agree, it looks pretty, but where are the real world testing results? Proof that it adds power and fuel mileage?

found it in YouTube under "testing side gapping spark plugs" sorry I don't know how to post it

the vid I saw showed the spark I'll try to find it, i'll have to ask wife how to post it though i'm not good with that

This is the two Zippers Gen 2 cams.

The OP has a Gen 2 M8, so there are only a few choices for cams.

He mentioned what is out there right now. That is unless there's some others I haven't come across yet.

Something else to think about.  Aviation has side strap plugs and are designed that way.  In the video is a normal aviation plug.  Notice the side of the center electrode is round and the inside of the strap matches this radius?  Top strap electrodes are positioned in such a way that the flat of the strap mirrors the flat of the top of the electrode.  Remove the top portion of the strap and now you have a flat electrode against the radius of the center.

The correct way to gap an automative plug is to set the distance of the electrodes but it is also important to square up the top strap electrode.  Why?  To make the gap even across the entire service area of the gap.  This gives the air gap the same resistance no matter where the spark actually jumps this gap.  Flat strap against a round edge defeats this purpose. 

https://youtu.be/4WMpMcyMKgs?si=SC0suKEcVVE-Aqy4

I would be very interested in seeing back to back dyno results, and proof at the track. Not sure I would go thru the trouble for one or two horsepower on the dyno, except for track use. I can use all the help I can get!
Not sure it would make much difference on the street when mostly short shifting at 3000 rpm on these tractor motors. But I am open to being proven wrong again.

The CR 485 seems decent in a lot of 117's, 139 Horsepower and 139 Torque from bolt on parts, the CR515 I thought was more for bigger cubes, mad stuff these M8's can produce with parts and tune.
Those dyno guys have a few charts to check out and APE downunder are getting some decent packages together, dunno about your specific engine but cubes is cubes even if your heads flow better than last year's model.